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Fingerprint Evidence
13 years ago
"...the majority of all crime is committed by habitual criminals who have been arrested or imprisoned before...their fingerprints are on file, and...a single fingerprint left anywhere about the scene of a crime may enable the experts to tell just who committed the crime."
-T. Dickerson Cooke, The Blue Book of Crime, 1953.
Fingerprint on knife blade 
Fingerprints are one of the best forms of physical evidence. A fingerprint can conclusively identify both offenders and victims. State wide, and soon, nation wide databases are available for rapid computerized searching. There are a number of methods of processing for fingerprints, some of best can be found below.
"On the Skin-Furrows of the Hand" (Historic Article)

In an effort to provide our readers with important or significantly historical information on fingerprints and crime scene investigation, we are beginning a new series of reprints of articles, reprinted with permission of the IAI Library from other publications. You might want to start a binder or notebook to save these articles for future reference. We decided to start with the article which truly started the world looking at fingerprints in a new way. Almost all fingerprint examiners know about this article, but few have had the opportunity to read it. It is not easy to find a copy of Nature from 1880.

In looking over some specimens of "prehistoric" pottery found in Japan I was led, about a year ago, to give some attention to the character of certain finger-marks which had been made on them while the clay was still soft. Unfortunately all of those which happened to come into my possession were too vague and ill-defined to be of much use, but a comparison of such finger-tip impressions made in recent pottery led me to observe the characters of the skin-furrows in human fingers generally. From these I passed to the study of the finger-tips of monkeys, and found at once that they presented very close analogies to those of human beings. I have here few opportunities of prosecuting the latter study to much advantage, but hope to present such results as I may attain in another letter. Meanwhile I would venture to suggest to others more favourably situated that careful study of the lemurs, &c., in this connection, as an additional means of throwing light on their interesting genetic relations.

A large number of nature-prints have been taken by me from the fingers of people in Japan, and I am at present collecting other from different nationalities, which I hope may aid students of ethnology in classification. Some few interesting points may here be mentioned by way of introduction.

Some individuals show quite a symmetrical development of these furrow. In these cases all the fingers of one hand have a similar arrangement of lines, while the pattern is simply reversed on the other hand. A Gibraltar monkey (Macacus innus) examined by me had this arrangement. A slight majority of the few Europeans I have been able to examine here have it also.

An ordinary botanical lens is of great service in bringing out these minor peculiarities. Where the loops occur the innermost lines may simply break off and end abruptly; they may end in self-returning loops, or, again, they may go on without breaks after turning round upon themselves. Some lines also join or branch like junctions in a railway map. 

     Please stay tuned for the next installment...

13 years ago
All these varieties, however, may be compatible with the general impression of symmetry that the two hands give us when printed from.

In a Japanese man the lines on both thumbs form similar spiral whorls; those of the left fore-finger form a peculiar oval whorl, while those of the right corresponding finger form an open loop having a direction quite opposite to that of the right fore-finger in the previous example. A similar whorl is found on both middle fingers instead of a symmetrically reversed whorl. The right ring-finger again has an oval whorl, but the corresponding left finger shows an open loop.

The lines at the ulno-palmar margin of this particular Japanese are of the parallel sort in both hands, and are quite symmetrical, thus differing from the Englishman's considerably. These instances are not intended to stand for typical patterns of the two peoples, but simply as illustrations of the kind of facts to be observed. My method of observation was at first simply to examine fingers closely, to sketch the general trend of the curves as accurately as possible, recording nationally, sex, colour of eyes and hair, and securing a specimen of the latter. I passed from this to "nature-printing," as ferns are often copied.

A common slate or smooth board of any kind, or a sheet of tine, spread over very thinly and evenly with printer's ink, is all that is required. The parts of which impressions are desired are pressed down steadily and softly, and then are transferred to slightly damp paper. I have succeeded in making very delicate impressions on glass. They are somewhat faint indeed, but would be useful for demonstrations, as details are very well shown, even down to the minute pores. By using different colours of ink useful comparisons could be made of two patterns by superposition. These might be shown by magic lantern. I have had prepared a number of outline hands with blank forms for entering such particulars of each case as may be wanted, and attach a specimen of hair for microscopic examination. Each finger-tip may best be done singly, and people are uncommonly willing to submit to the process. A little hot water and soap remove the ink. Benzine is still more effective. The dominancy of heredity through these infinite varieties is sometimes very striking. I have found unique patterns in a parent repeated with marvellous accuracy in his child. Negative results, however, might prove nothing to parentage, a caution which it is important to make.

I am sanguine that the careful study of these patterns may be useful in several ways.

  1. We may perhaps be able to extend to other animals the analogies found by me to exist in the monkeys.
  2. These analogies may admit of further analysis, and may assist, when better understood, in ethnological classifications.
  3. It so, those which are found in ancient pottery may become of immense historical importance.
  4. The fingers of mummies, by special preparation, may yield results for comparison. I am very doubtful, however, of this.
  5. When bloody finger-marks or impressions of clay, glass, &c., exist, they may lead to the scientific identification of criminals. Already I have had experience in two such cases, and found useful evidence from these marks. In one case greasy finger-marks revealed who had been drinking some rectified spirit. The pattern was unique, and fortunately I had previously obtained a copy of it. They agreed with microscopic fidelity. In another case sooty finger-marks of a person climbing a white wall were of great use a negative evidence. Other cases might occur in medico-legal investigations, as when the hands only of some mutilated victim were found. If previously known they would be much more precise in value than the standard mole of penny novelists. If unknown previously, heredity might enable an expert to determine the relatives with considerable probability in many cases, and with absolute precision in some. Such a case as that of the Claimant even might not be beyond the range of this principle. There might be a recognisable Tichborne type, and there might be an Orton type, to be one or other of which experts might relate the case. Absolute identity would prove descent in some circumstances.
13 years ago
I have heard, since coming to these general conclusions by original and patient experiment, that the Chinese criminals from early times have been made to give the impressions of their fingers, just as we make ours yield their photographs. I have not yet, however, succeeded in getting any precise or authenticated facts on that point. That the Egyptians caused their criminals to seal their confessions with their thumb-nails, just as the Japanese do now, a recent discovery proves. This is however quite a different matter, and it is curious to observe that in our country servant-girls used to stamp their sealed letters in the same way. There can be no doubt as to the advantage of having, besides their photographs, a nature-copy of the for-ever-unchanging finger-furrows of important criminals. It need not surprise us to find that the Chinese have been before us in this as in other matters. I shall be glad to find that it is really so, as it would only serve to confirm the utility of the method, and the facts which may thus have been accumulated would be a rich anthropological mine for patient observers.

Henry Faulds, Tsukiji Hospital, Tokio, Japan

[Some very interesting examples of nature-printed finger-tips accompanied this letter. — Ed.]

"Skin Furrows of the Hand"
13 years ago
by W.J. Herschel (Nov. 25, 1880)

This is the second article in our series of significant, historical information on fingerprints and crime scene investigation. This is from a copy I (K. Saviers) made from an issue of Nature at the Library at the University of California, Irvine. You might want to start a binder or notebook to save these articles for future reference.

Allow me to contribute the information in my possession in furtherance of the interesting study undertaken by your Japan correspondent [vol. xxi, p. 605].

I have been taking sign-manuals by means of finger-marks for now more than twenty years, and have introduced them for practical purposes in several ways in India with marked benefit.

The object has been to make all attempts at personation, or at repudiation of signatures, quite hopeless wherever this method is available.

(1) First I used it for pensioners whose vitality has been a distracting problem to Government in all countries. When I found all room for suspicion effectually removed here, I tried it on a larger scale in the several (2) registration offices under me, and here I had the satisfaction of seeing every official and legal agent connected with these offices confess that the use of these signatures lifted off the ugly cloud of suspiciousness which always hangs over offices in India. It put a summary and absolute stop to the very idea of either personation of repudiation from the moment half a dozen men had made their marks and compared them together. (3) I next introduced them into the jail, where they were not un-needed. On commitment to jail each prisoner had to sign with his finger. Any official visitor to the jail after that could instantly satisfy himself of the identity of the man whom the jailor produced by requiring him to make a signature on the spot and comparing it with that which the books showed.

The ease with which the signature is taken and the hopelessness of either personation or repudiation are so great that I sincerely believe that the adoption of the practice in places and professions where such kinds of fraud are rife is a substantial benefit to morality.

I may add that by comparison of the signatures of persons now living with their signatures made twenty years ago, I have proved that that much time at least makes no such material change as to affect the utility of the plan.

For instance, if it were the practice on enlisting in the army to take (say) three signatures - one to stay with the regiment, one to go to the Horse Guards, and one to the police at Scotland Yard - I believe a very appreciable diminution of desertions could be brought about by the mere fact the identification was becoming simply a matter of reference to the records.

And supposing that there existed such as thing as a finger-mark of Roger Tichborne, the whole Orton imposture would have been exposed in the full satisfaction of the jury in a single sitting by requiring Orton to make his own mark for comparison.

The difference between the general character of the rugć of Hindoos and of Europeans is as apparent as that between male and female signatures, but my inspection of several thousands has not led me to think that it will ever be practically safe to say of any single person's signature that it is a woman's, or a Hindoo's, or not a male European's. The conclusions of your correspondent seem, however, to indicate greater possibilities of certainty. In single families I find myself the widest varieties.

15, St. Giles, Oxford, November 13, W.J. Herschel

P.S.-It would be particularly interesting to hear whether the Chinese have really used finger-marks in this way. Finger-dips (mere blots) are common in the East, as "marks."

Fingerprint Evidence
13 years ago

A brief explanation of the techniques involved in gathering and using fingerprint evidence.

In this day and age of high-tech crime-solving methods, especially DNA typing, the lowly art of fingerprint identification sometimes seems lost. In fact, fingerprint evidence is highly reliable and particularly accessible to juries: You don't need a Ph.D. or a scientific lecture on genetics to understand that your own fingers contain a contour map of ridges and whorls that is completely unique. And unlike the theories behind DNA matching, no one seriously doubts this assumption.

Matching Fingerprints

Fingerprint evidence rests on two basic principles:

  • A person's "friction ridge patterns" (the swirled skin on their fingertips) don't change.
  • No two people have the same pattern of friction ridges.

Police officers can use fingerprints to identify defendants and crime victims if a print matches one already on file. (Today, the FBI has a collection of prints that numbers in the millions.) People's fingerprints can be on file for a variety of reasons. For example, people may be fingerprinted when they are arrested, or when they begin certain occupations. And it is increasingly popular for parents to ask local police departments or schools to fingerprint their young children, a grim reminder that children who are abducted or are the victims of other heinous crimes often cannot be identified otherwise.

How Fingerprints Are Found

Friction ridges contain rows of sweat pores, and sweat mixed with other body oils and dirt produces fingerprints on smooth surfaces. Fingerprint experts use powders and chemicals to make such prints visible. The visibility of a set of prints depends on the surface from which they're lifted; however, with the help of computer enhancement techniques that can extrapolate a complete pattern from mere fragments, and laser technology that can read otherwise invisible markings, fingerprint experts increasingly can retrieve identifiable prints from most surfaces.

The age of a set of fingerprints is almost impossible to determine. Therefore, defendants often try to explain away evidence that their fingerprints were found at crime scenes by testifying that they were at the scene and left the prints at a time other than the time of a crime.

The History of Fingerprints
13 years ago
Why Fingerprint Identification?Fingerprints offer an infallible means of personal identification. That is the essential explanation for their having supplanted other methods of establishing the identities of criminals reluctant to admit previous arrests.  

The science of fingerprint Identification stands out among all other forensic sciences for many reasons, including the following:   

  • Has served all governments worldwide during the past 100 years to provide accurate identification of criminals. No two fingerprints have ever been found alike in many billions of human and automated computer comparisons.  Fingerprints are the very basis for criminal history foundation at every police agency.

  • Established the first forensic professional organization, the International Association for Identification (IAI), in 1915.

  • Established the first professional certification program for forensic scientists, the IAI's Certified Latent Print Examiner program (in 1977), issuing certification to those meeting stringent criteria and revoking certification for serious errors such as erroneous identifications.  

  • Remains the most commonly used forensic evidence worldwide - in most jurisdictions fingerprint examination cases match or outnumber all other forensic examination casework combined.

  • Continues to expand as the premier method for identifying persons, with tens of thousands of persons added to fingerprint repositories daily in America alone - far outdistancing similar databases in growth.

  • Outperforms DNA and all other human identification systems to identify more murderers, rapists and other serious offenders (fingerprints solve ten times more unknown suspect cases than DNA in most jurisdictions).   

  • Other visible human characteristics change - fingerprints do not. In earlier civilizations, branding and even maiming were used to mark the criminal for what he was. The thief was deprived of the hand which committed the thievery. The Romans employed the tattoo needle to identify and prevent desertion of mercenary soldiers.  

    Before the mid-1800s, law enforcement officers with extraordinary visual memories, so-called "camera eyes," identified previously arrested offenders by sight. Photography lessened the burden on memory but was not the answer to the criminal identification problem. Personal appearances change.

    Around 1870, a French anthropologist devised a system to measure and record the dimensions of certain bony parts of the body. These measurements were reduced to a formula which, theoretically, would apply only to one person and would not change during his/her adult life.

  • This Bertillon System, named after its inventor, Alphonse Bertillon, was generally accepted for thirty years. But it never recovered from the events of 1903, when a man named Will West was sentenced to the U.S. Penitentiary at Leavenworth, Kansas. You see, there was already a prisoner at the penitentiary at the time, whose Bertillon measurements were nearly the same, and his name was William West.

    Upon investigation, there were indeed two men who looked exactly alike, but were allegedly not related. Their names were Will and William West respectively. Their Bertillon measurements were close enough to identify them as the same person. However, a fingerprint comparison quickly and correctly identified them as two different people. (Per prison records discovered later, the West men were apparently identical twin brothers and each had a record of correspondence with the same immediate family relatives.)

13 years ago

Picture writing of a hand with ridge patterns was discovered in Nova Scotia. In ancient Babylon, fingerprints were used on clay tablets for business transactions. In ancient China, thumb prints were found on clay seals.

Chinese Clay Seal

In 14th century Persia, various official government papers had fingerprints (impressions), and one government official, a doctor, observed that no two fingerprints were exactly alike.

Marcella Malpighi
1686 - MalpighiIn 1686, Marcello Malpighi, a professor of anatomy at the University of Bologna, noted in his treatise; ridges, spirals and loops in fingerprints. He made no mention of their value as a tool for individual identification. A layer of skin was named after him; "Malpighi" layer, which is approximately 1.8mm thick.
Prof Purkinje
1823 - Purkinje

In 1823, John Evangelist Purkinje, a professor of anatomy at the University of Breslau, published his thesis discussing 9 fingerprint patterns, but he too made no mention of the value of fingerprints for personal identification.

13 years ago
1856 - Hershel
The English first began using fingerprints in July of 1858, when Sir William Herschel, Chief Magistrate of the Hooghly district in Jungipoor, India, first used fingerprints on native contracts. On a whim, and with no thought toward personal identification, Herschel had Rajyadhar Konai, a local businessman, impress his hand print on a contract.
Konai - Herschel Contract
Sir Wm. Herschel

The idea was merely "... to frighten [him] out of all thought of repudiating his signature." The native was suitably impressed, and Herschel made a habit of requiring palm prints--and later, simply the prints of the right Index and Middle fingers--on every contract made with the locals. Personal contact with the document, they believed, made the contract more binding than if they simply signed it. Thus, the first wide-scale, modern-day use of fingerprints was predicated, not upon scientific evidence, but upon superstitious beliefs.

As his fingerprint collection grew, however, Herschel began to note that the inked impressions could, indeed, prove or disprove identity. While his experience with fingerprinting was admittedly limited, Sir Herschel's private conviction that all fingerprints were unique to the individual, as well as permanent throughout that individual's life, inspired him to expand their use.

Herschel's FPs recorded over a period of 57 yrs
Herschel's fingerprints recorded over a period of 57 years

1880 - Faulds

During the 1870's, Dr. Henry Faulds, the British Surgeon-Superintendent of Tsukiji Hospital in Tokyo, Japan, took up the study of "skin-furrows" after noticing finger marks on specimens of "prehistoric" pottery. A learned and industrious man, Dr. Faulds not only recognized the importance of fingerprints as a means of identification, but devised a method of classification as well.

In 1880, Faulds forwarded an explanation of his classification system and a sample of the forms he had designed for recording inked impressions, to Sir Charles Darwin. Darwin, in advanced age and ill health, informed Dr. Faulds that he could be of no assistance to him, but promised to pass the materials on to his cousin, Francis Galton.

Also in 1880, Dr. Faulds published an article in the Scientific Journal, "Nature" (nature). He discussed fingerprints as a means of personal identification, and the use of printers ink as a method for obtaining such fingerprints. He is also credited with the first fingerprint identification of a greasy fingerprint left on an alcohol bottle.

Dr. Henry Faulds 

13 years ago
1882 - Thompson
In 1882, Gilbert Thompson of the U.S. Geological Survey in New Mexico, used his own fingerprints on a document to prevent forgery. This is the first known use of fingerprints in the United States.  Click the image below to see a larger image of an 1882 receipt issued by Gilbert Thompson to "Lying Bob" in the amount of 75 dollars.

Thompson Receipt
Samuel L. Clemens
Twain (Clemens)
1883 - Mark Twain (Samuel L. Clemens)
In Mark Twain's book, "Life on the Mississippi", a murderer was identified by the use of fingerprint identification. In a later book by Mark Twain, "Pudd'n Head Wilson", there was a dramatic court trial on fingerprint identification. A more recent movie was made from this book.  Sir Francis Galton
1888 - Galton  Sir Francis Galton, a British anthropologist and a cousin of Charles Darwin, began his observations of fingerprints as a means of identification in the 1880's.  
1891 - Vucetich

Juan Vucetich, an Argentine Police Official, began the first fingerprint files based on Galton pattern types. At first, Vucetich included the Bertillon System with the files. (see Bertillon below)  

1892 - Vucetich & Galton

Juan Vucetich made the first criminal fingerprint identification in 1892. He was able to identify a woman by the name of Rojas, who had murdered her two sons, and cut her own throat in an attempt to place blame on another.  Her bloody print was left on a door post, proving her identity as the murderer.

Sir Francis Galton published his book, "Fingerprints", establishing the individuality and permanence of fingerprints. The book included the first classification system for fingerprints.

Galton's primary interest in fingerprints was as an aid in determining heredity and racial background. While he soon discovered that fingerprints offered no firm clues to an individual's intelligence or genetic history, he was able to scientifically prove what Herschel and Faulds already suspected: that fingerprints do not change over the course of an individual's lifetime, and that no two fingerprints are exactly the same. According to his calculations, the odds of two individual fingerprints being the same were 1 in 64 billion.

Galton identified the characteristics by which fingerprints can be identified. These same characteristics (minutia) are basically still in use today, and are often referred to as Galton's Details.
13 years ago
1897 - Haque & Bose
On 12 June 1987,  the Council of the Governor General of India approved a committee report that fingerprints should be used for classification of criminal records.  Later that year, the Calcutta (now Kolkata) Anthropometric Bureau became the world's first Fingerprint Bureau.  Working in the Calcutta Anthropometric Bureau (before it became the Fingerprint Bureau) were Azizul Haque and Hem Chandra Bose.  Haque and Bose are the two Indian fingerprint experts credited with primary development of the Henry System of fingerprint classification (named for their supervisor, Edward Richard Henry).  The Henry classification system is still used in all English-speaking countries. Sir Edward Richard Henry
1901 - Henry
Introduction of fingerprints for criminal identification in England and Wales, using Galton's observations and revised by Sir Edward Richard Henry.  1902First systematic use of fingerprints in the U.S. by the New York Civil Service Commission for testing. Dr. Henry P. DeForrest pioneers U.S. fingerprinting.  1903The New York State Prison system began the first systematic use of fingerprints in U.S. for criminals. 
1904The use of fingerprints began in Leavenworth Federal Penitentiary in Kansas, and the St. Louis Police Department. They were assisted by a Sergeant from Scotland Yard who had been on duty at the St. Louis World's Fair Exposition guarding the British Display.  Sometime after the St. Louis World's Fair, the International Association of Chiefs of Police (IACP) created America's first national fingerprint repository, called the National Bureau of Criminal Identification.  US Army Seal 1905U.S. Army begins using fingerprints.

U.S. Department of Justice forms the Bureau of Criminal Identification in Washington, DC to provide a centralized reference collection of fingerprint cards.

Two years later the U.S. Navy started, and was joined the next year by the Marine Corp. During the next 25 years more and more law enforcement agencies join in the use of fingerprints as a means of personal identification. Many of these agencies began sending copies of their fingerprint cards to the National Bureau of Criminal Identification, which was established by the International Association of Police Chiefs.
US Navy Seal 1907U.S. Navy begins using fingerprints.

U.S. Department of Justice's Bureau of Criminal Identification moves to Leavenworth Federal Penitentiary where it is staffed at least partially by inmates. 
USMC Seal 1908U.S. Marine Corps begins using fingerprints.
13 years ago

Edmond Locard wrote that if 12 points (Galton's Details) were the same between two fingerprints, it would suffice as a positive identification.  Locard's 12 points seems to have been based on an unscientific "improvement" over the eleven anthropometric measurements (arm length, height, etc.) used to "identify" criminals before the adoption of fingerprints.   

1924In 1924, an act of congress established the Identification Division of the FBI. The IACP's National Bureau of Criminal Identification and the US Justice Department's Bureau of Criminal Identification consolidated to form the nucleus of the FBI fingerprint files.  

By 1946, the FBI had processed 100 million fingerprint cards in manually maintained files; and by 1971, 200 million cards.

With the introduction of AFIS technology, the files were split into computerized criminal files and manually maintained civil files.  Many of the manual files were duplicates though, the records actually represented somewhere in the neighborhood of 25 to 30 million criminals, and an unknown number of individuals in the civil files.


The FBI's Integrated AFIS (IAFIS) in Clarksburg, WV has more than 49 million individual computerized fingerprint records for known criminals.  Old paper fingerprint cards for the civil files are still manually maintained in a warehouse facility (rented shopping center space) in Fairmont, WV, though most enlisted military service member fingerprint cards received after 1990, and all military-related fingerprint cards received after 19 May 2000, have now been computerized and can be searched internally by the FBI.  In some future build of IAFIS, the FBI may make such civil file AFIS searches available to other federal crime laboratories. 

All US states and most larger cities have their own AFIS databases, each with a subset of fingerprint records that is not stored in any other database.  Thus, law enforcement fingerprint interface standards are very important to enable sharing records and mutual searches for identifying criminals. 
A Brief History of Fingerprinting in the U.S.
13 years ago

As we all know (those of us who actually paid attention to the history lectures in our early fingerprint classes), the first published account of the use of fingerprints as a practical means of identification was the letter written by Dr. Henry Faulds to the British magazine Nature, printed in the October 28, 1880 edition. William Herschel had been using fingerprints as a means of identification in India since 1858 and had written to England suggesting expansion of his program, but no public mention had been made.

After Faulds' letter, however, individuals around the world took note. One such individual was Gilbert Thompson of the United States Geological Survey. Thompson was sent on an expedition to New Mexico with a crew of surveyors and explorers in 1882. Apparently, a number of his crew were not trustworthy, and drafts began showing up for payment bearing Thompson's forged signature. To protect against these forgeries, Thompson began using his thumbprint on the drafts, with his signature on top of his thumbprint. This marks the first official use of fingerprints in the United States.

Meanwhile, in New York City, a problem was growing in regards to the civil service hiring process and in 1900, a scandal erupted when several individuals were implicated in a scheme of hiring educated (but unethical) persons to take the civil service exams. Dr. Henry P. deForest solved the problem by fingerprinting applicants when they took the examinations. The first set of fingerprints taken were from one James Johnson on December 19, 1902. This was the first use of fingerprints by a government agency in the U.S.

In the summer of 1902, Charles K. Baker of the New York State Prison Department, accompanied by Dr. R. B. Lamb of the State Hospital, went to England to study the fingerprint system in use there. They returned and shared their new-found knowledge with James H. Parke, furnishing him with copies of Finger Prints by Sir Francis Galton and Classification and Uses of Finger Prints by Sir E. R. Henry. Parke studied these books and inaugurated the use of fingerprints in the New York State Prison Department in March of 1903. This was the first use of fingerprints for criminal identification in the United States.

Of course, John Kenneth Ferrier of Scotland Yard taught fingerprints to nine Americans and Canadians at the World's Fair in St. Louis in 1904, after which the science of fingerprints was rapidly adopted by law enforcement agencies throughout the United States.

The first criminal conviction based on fingerprint evidence was the case of Thomas Jennings. Jennings was charged with the murder of Charles Hiller, committed while perpetrating a burglary. This case in 1911 marks the first judicial ruling in the U.S. on the admissibility of a fingerprint identification.

The International Association for Identification was formed in 1915. At the time, it consisted primarily of Bertillon clerks, but as fingerprints were rapidly replacing anthropological measurements, the main focus of the IAI quickly changed. The IAI thus played a pivotal role in the rapid spread and acceptance of fingerprints in the U.S.

The first authoritative textbook on fingerprints in the United States was The Finger Print Instructor by Frederick Kuhne, published in 1916. The Institute of Applied Science also opened its doors and began widespread training in 1916.

The final step in bringing fingerprints to national prominence was the formation of the FBI Fingerprint Section under A. J. Renoe in 1924.

The Science Of Fingerprint Identification
13 years ago

By Andre A. Moenssens1

Fingerprint identification has been around for a long time. It has nearly a century of court acceptance in the United States. Yet, in the aftermath of United States Supreme Court cases like Daubert v. Merrell Dow Pharmaceuticals (1993) and Kumho Tire v. Carmichael (1999), requiring courts to determine the reliability (validity) of underlying techniques before admitting expert opinion based on it, questions are bound to be raised about the scientific legitimacy of many of the techniques commonly used in crime laboratories, fingerprint identification among them.

Skilled examiners of fingerprint evidence agree that the process of comparing latent fingerprints of unknown origin with inked impressions of known origin is an "art," rather than a science. It requires an examiner to assess, on the basis of experience in dealing with thousands of fingerprints, what parts of an incomplete and partially blurred latent print show visible friction ridge detail that can be used for identification purposes. But whether fingerprint identification is "art" or "science" is clearly no longer relevant to a Daubert inquiry. What needs to be examined is whether the underlying premises upon which fingerprint identification are based have been empirically validated. And these premises are three-fold: (1) the friction ridge detail of the epidermis on the palm side of the hands
2 remains unchanged during the lifetime of an individual, except for accidental or intentional scarification or alteration; (2) friction ridge pattern areas exhibit so much variety of detail that no two patterns are ever found to be exactly the same on the digits (or palms or soles of feet) of one individual or on the digits (or palms or soles of feet) of other individuals; (3) while these friction ridge patterns exhibit an infinite variety of detail, they nevertheless fall within certain broad classes or categories that permit police to store and retrieve millions of prints according to classification formulae.

Premise one has clearly stood the test of time and experience. It has been established in over 100 years of accumulated experience that friction ridge patterns remain unchanged naturally in their ridge detail during the lifetime of an individual. The ridge patterns begin to form during pre-natal life and are fully formed by the seventh month of fetal life.

Premise three has equally proved to be true by verification and experience. We have been able to deal with millions of accumulated fingerprint cards by devising classification formulae based on pattern types and subgroups
3 until the advent of automated computer and retrieval systems, referred to generically as AFIS4 systems in "the trade," made such classification formulae unnecessary.

Premise number two, that all fingerprints are unique and never duplicated in the universe, is a premise that is harder to prove empirically, despite the fact that all fingerprint examiners fervently believe in it. However, in all of the human experience with fingerprints world-wide, no two fingerprints from different digits have ever been found to match exactly. It has been argued that, since millions of sets of prints have been stored in fingerprint files as voluminous as, say, the FBI Identification Section and no exact duplication of friction skin detail has been encountered in these fingerprint repositories, individuality is clearly proved. The problem with this assertion is that it does not stand the test of reason. The millions of sets of prints were never compared against one another for possible duplication of friction ridge patterns. Filing and retrieving prints from such a massive file only results in an examination of a comparatively small number of sets of prints: those with a matching, or approximately matching, classification formula.

13 years ago
There is, however, respectable empirically established evidence of the uniqueness of fingerprint patterns. Studies done by many examiners have shown that the fingerprints of identical twins are different, as are the prints of triplets, quadruplets, and quintuplets. In that sense, fingerprint identification has been found to be even more discriminating than the vaunted DNA (deoxyribonucleic acid) "fingerprinting" method, which cannot distinguish, by today’s technology, between the DNA of identical twins. Since inherited traits for similarity in patterns and sub-pattern types are the most common among people who are very closely related, the difference in the prints of such persons certainly can be taken as empirical evidence of fingerprint individuality. Might we not infer from that experience that all fingerprints of different digits are, indeed, different?

Persons skilled in fingerprint identification, who have literally viewed, scanned, and studied tens--if not hundreds--of thousands of individual patterns, do not doubt this. Clearly, if exact pattern duplication were to exist in the world, at least a single instance of this would have been discovered by now. While such claims have been made often, every case, when examined, has established that the prints of different digits that were allegedly "the same" exhibited indeed clearly visible differences that would not have lead an examiner to an erroneous identification. There simply was no duplication of individual ridge detail in prints from different digits.

At he time when fingerprint evidence was first admitted by courts, such empirical evidence or experience in dealing with millions of fingerprint records was not available. If the courts at that era which confronted fingerprint identification evidence first [in Argentina (1892), India (1897), France (1902), and subsequently in England and the United States] had been required to satisfy a Daubert-like decision, perhaps fingerprint identifications would not have been deemed admissible in those early years. With the data that is available today, however, it would be rather ludicrous to argue that the premises underlying fingerprint identification have not been scientifically validated in the face of the accumulated experience of the millions of fingerprints that have been scrutinized by experts.

But there is, today, an opportunity to prove the underlying principle of individuality empirically in a manner that was not available in the past. The tremendous computer data bases holding millions of individual finger impressions can today be searched to determine whether pattern duplication exists. While experience has dictated such research is not necessary, the purists (or skeptics) could be satisfied by a rather simple research program that asks our AFIS systems to search, say, a partial individual print of a known person and compare the print against the entire data base. Competent fingerprint examiners feel confident that when the "statistical matches" the computer is bound to throw up are visually examined by them for concordance of individual ridge detail, no two prints from different digits will be found to match.
1 Prof. Moenssens is the author of the books Fingerprint Techniques (1971) and of Fingerprints and the Law (1969), now out of print but being readied for updated reissue as a single volume Fingerprint Identification: Techniques and Evidence. He is also the senior co-author of Scientific Evidence in Civil and Criminal Cases, now in its fourth edition.

2 And also on the soles (plantar surfaces) of the feet.

3 The most common of those classification systems were (1) the Henry System and its subsequent modifications, used widely in countries that have the common law of Great Britain as the basis for their legal systems; and (2) the Vucetich System and its derivatives, used elsewhere.

4 Automated Fingerprint Identification System.
Latent Print Powders (How, When and with What?)
13 years ago

How and When to Dust with Regular Powders

For many crime scene investigators, more than half of the powder used is regular, nonmagnetic powder. It can be used on windows, counter-tops, television sets and many other items moved or touched at residential burglary scenes. At commercial burglary scenes, it can be used on metal file cabinets, painted doors, broken glass and metal window frames. Regular powders can be applied to the painted surfaces, glass windows and mirrors in recovered stolen vehicles. At most of the day-to-day crime scenes visited, the crime scene investigator will have the opportunity to use regular powder on many surfaces.

Regular powders are available in colors such as black, silver/gray, Bichromatic™ and white. Choose a color which will provide sufficient contrast with the background surface to obtain a clear photograph of the latent print. Black is one of the most popular colors used because once the latent print is lifted and placed on a backing card, the ridges of the latent print will be black against the white backing card. This makes it easy for the latent print examiner to compare the black ridges of the latent print to the black ridges of the inked print on the rolled card.

However, to be able to photograph the latent print against a dark-colored background, silver/gray powder can be used. It will be necessary to place it on a black backing card when it is lifted. For some latent print examiners, this can cause difficulties having to compare the light colored ridges of the latent print to the dark colored ridges of the inked print. There is also the necessity of having to carry two jars of powder, two brushes and two sets of backing cards. To solve this problem, many crime scene technicians use Bichromatic™ latent print powder.

Bichromatic™ latent print powder is a combination of black and silver/gray powder which can be dusted on a light or dark surface. On a light colored surface, the latent print will appear dark so it can be seen and photographed easily. On a dark-colored surface, it will appear light. When lifted with tape and placed on a white backing card, the latent print will appear dark. This solves the problem for all involved. The crime scene investigator only has to carry one powder, one brush and one color of backing cards. The latent prints will be visible on a light or dark colored surface and the latent print examiner only has to compare the dark ridges of the latent print to the dark ridges of the inked print.

Now that a color has been chosen, the method of application must be chosen. Powders are applied with brushes. Materials used to make brushes include camelhair, squirrelhair and fiberglass. Most crime scene investigators prefer a fiberglass brush, such as the Zephyr® Fiberglass Brush, because it is easy to use, the powder can be applied quickly and the chances of damaging the latent print are fewer. Some crime scene investigators were taught to use camelhair brushes and that is all they want to use. Others were taught with a fiberglass brush and nothing will convince them to switch to a camel- or squirrelhair brush.

Regardless of which brush is used, the technique of the crime scene investigator is very important. Just as one investigator can get excellent results with a fiberglass brush because of proper training and sufficient practice, another investigator will get poor results because of lack of training and insufficient practice.

Here are a few helpful hints in dealing with latent print powder. Keep the powder dry so that moisture does not cause it to become lumpy or hard. If the powder does turn into a solid lump, shake the jar (with the lid on) to break it loose. If necessary, place a couple of ball bearings or, better yet, a couple of balls from an old Pachinco game, in the jar to keep the powder loose.

13 years ago

While the brush can be dipped directly into the jar of powder, it is better to construct a small tray out of thin cardboard, such as an 8" x 8" fingerprint card. A small portion of powder can be poured into this small tray to facilitate loading the brush with powder. Others do not feel that this is necessary and load the brush with powder by dipping it into the jar. It is easy to get too much powder on the brush this way or to knock over the jar of powder. If you do decide to load your brush directly from the jar, keep the jar half full. This leaves room to move the brush around inside the jar to knock off the excess powder.

When applying powder to a surface, start with a light touch. It is easy to add more powder, if necessary, but it can be difficult to take away excess powder. Use the brush with gentle, light strokes. Latent print residue can easily be wiped away with too heavy of a stroke.

How and When to Dust with Magnetic PowdersMagnetic powders are used at special times when better results will be obtained than if regular powders are used. Generally, better latent prints will be developed on shiny magazine covers or boxes with a coated surface when using magnetic powders rather than regular powders. Some plastic materials, such as food storage containers and plastic baggies are choice surfaces for magnetic powders.

When dusting with magnetic powders, it is necessary to use a magnetic powder applicator. The applicator has a magnet in the end to pick up and hold the magnetic powder in the shape of a fuzzy ball. Apply the powder by lightly "brushing" it over the surface of the evidence. Do not let the tip of the applicator touch the surface. Only the ball of powder should touch the surface. If the tip of the applicator should touch the surface, it may wipe away or mark the latent print.

When you have finished dusting the surface, hold the magnetic applicator over the open jar of powder and pull up on the knob at the opposite end of the applicator. This draws up the magnet away from the end with the powder on it and the powder will fall loose into the jar. Any powder which falls off of the surface or misses the jar can be picked up with the magnetic applicator and put back into the jar. Magnetic powder is economical as very little is wasted.

How to Lift a Latent Print After DustingLatent prints developed with either type of powder can generally be lifted with adhesive tape, such as rolls of frosted or clear tape, poly tape or Handi-Lifts™ and Lightning Lifts™ pre-cut tape strips. The process is simple. After the latent print has been developed with powder, press a piece of tape on the surface and rub it to make sure complete contact is made. Be sure that the size of the piece of tape is large enough to cover the latent print.

Remove the piece of tape from the surface and press it onto a latent print backing card. Use a white backing card for latent prints developed with black or Bichromatic™ powders. Use a black backing card for latent prints developed with silver/gray or white powders. Handi-Lifts™ are available with a white, black or transparent backer.

It is important to make notations on the backing card to indicate from where the latent print was recovered. Preprinted backing cards have boxes to fill in for the date, time, case number and other information regarding the latent print lifted. It is suggested that you write your initials half on the lift tape and half on the backing card. This shows you have put the tape on the backing card and no one else tampered with it or put another piece of tape with another latent print on your backing card.

Another method to provide a chain of custody record is to use numbered backing cards. You would use a series of numbered backing cards at a crime scene. These numbers would be noted in your crime scene report. If any backing cards with the wrong number or no numbers appear in the group of backing cards with the case evidence, it may be a fabricated piece of evidence.

This has been a brief explanation of how to develop latent prints using regular and magnetic powders. There are many other methods for developing latent prints, such as fluorescent powders and dyes and other chemicals for developing latent prints on special surfaces. Check out our catalog for charts of sequential processing of latent prints on a variety of surfaces. FAX (800-588-03-99), e-mail ( or write for our free Chemical Processing of Latent Prints Technical Notes booklet. You can also access the technical notes from this booklet at our website:

Developing Prints on Adhesive Surfaces
13 years ago

This article is the seventh in a comprehensive series of articles on latent print development techniques written by Pat A. Wertheim, Director of Training for Forensic Identification Training Seminars, Ltd. Watch for future articles in each issue of Minutić and save these issues in a binder to compile a manual of fingerprint development techniques.

Processing adhesive surfaces for latent prints may be intimidating for a technician not often faced with surfaces such as tape, adhesive labels, or bumper stickers. But the sticky side of tape is one of the easiest and most productive surfaces to print ever encountered.

A method first reported in 1981 is dye staining with gentian violet, also known as crystal violet. See Identification News, February, 1981 for an article by Takashi Arima.

Gentian violet is generally purchased as a powder and dissolved in water prior to use. A solution of 0.1% (1 gram powder per 1000 ml water) is recommended. Although many technicians simply dissolve the powder in tap water and report fair results, the staining process works more dependably if distilled water is used and the solution is adjusted to a pH of 7 or 8 by the addition of a small amount (sometimes just a drop or two) of ammonia.

The tape is soaked in the solution for several minutes, then rinsed under running tap water. The dark purple dye stains sebaceous material and skin cells which have sloughed off of the person's fingers and palms and which have stuck to the adhesive side where the tape was touched. To the naked eye, the stained fingerprint appears to have purple ridges, but under a microscope, each ridge may be seen to be composed of tens of thousands of tiny stained skin cells.

The gentian violet process runs into problems on dark tape, however. A gentian violet print, even though unseen, may be transferred to fixed photographic paper by first wetting the paper, then placing the adhesive side of the tape on the paper, and lightly ironing the tape. However, many technicians prefer the small particle reagent method discussed below to dye stain transfer for dark tape.

A more recent method than gentian violet is the use of powder in a suspension of detergent and water. The first powder widely used was "Sticky-Side Powder," which is still the favorite of many examiners. This powder is purchased dry. One part powder, one part tap water, and one part Photo-Flo are mixed together to form a thick suspension solution, iridescent black in color and the consistency of buttermilk. This suspension may be applied to the adhesive surface by any of several methods.

One excellent method is to paint it on with a camelhair brush. Another method is to drag the tape through the suspension in a very shallow dish. Another method is to shake the suspension to a foamy state and move the tape through the foam. However done, the tape should be rinsed under running tap water within a minute or so of the application.

Many people report better results if the tape is rinsed in clean water before application of the Sticky-Side suspension. Prior rinsing lightens the background noise without significantly affecting the latent print itself.

For processing on dark tape, such as black electrical tape, substitute Small Particle Reagent powder for Sticky-Side Powder in the above formula. Sticky-Side Powder is too dark to be seen clearly on the black tape, but Small Particle Reagent has a lighter component which is visible.

Once developed, whether by gentian violet or by a powder suspension, prints on adhesive surfaces should be dried and photographed. Following that, the tape may be applied to a clear piece of plastic, such as a piece of a zip-lock bag, to protect the print.

If more than one process is desired, gentian violet should be used first. Any prints developed that way should be photographed, then the Sticky-Side Powder suspension applied. In many cases, however, technicians are choosing to forego gentian violet and use only the Sticky-Side Powder. Whatever the choice, these methods are both easy and productive. Mix some of each and spend a few minutes practicing on some adhesive surfaces around the office, and you will look forward to evidence containing tape, adhesive labels, bumper stickers, and other sticky surfaces.

In the next issue of Minutić, Pat will write about Small Particle Reagent.

Amido Black
13 years ago

Amido Black, also known as Naphthalene Blue-Black or Naphthalene Black 12B, is a protein dye, sensitive to the protein in blood. It will stain the protein residue in a blood-contaminated latent print and turn a blue-black color. It will not stain the normal constituents found in latent print residue so it should only be used in the case of blood-contaminated latent prints to be successful.


As with all chemicals, always read the MSDS (material safety data sheet) to learn about the safe handling and health hazards of each chemical. Gloves and protective clothing should be worn when using Amido Black. It should be mixed and used in a fume hood or with an appropriate respirator. Amido Black is not a carcinogen. Some of the solvents used to mix it are hazardous and/or flammable. Use the proper safety precautions in handling and disposal.

Mixing Instructions

Working Solution 1 gram Amido Black
50 ml Glacial Acetic Acid
450 ml Methanol

Weigh out 1 gram of Amido Black and place it in a one liter glass beaker. Place it on a magnetic stirrer. Add 50 ml of Glacial Acetic Acid and stir. When completely mixed, add 450 ml of Methanol and stir for at least 30 minutes. When completely mixed, store the solution in a glass bottle. Properly label the bottle.

Glacial Acetic Acid-Methanol Solution
100 ml Glacial Acetic Acid
900 ml Methanol

Pour 100 ml of Glacial Acetic Acid into a glass storage bottle. Add 900 ml of Methanol. Stir the solution until mixed. Properly label the bottle.

Glacial Acetic Acid-Distilled Water Solution
50 ml Glacial Acetic Acid
950 ml Distilled Water

Pour 50 ml of Glacial Acetic Acid into a glass storage bottle. Add 950 ml of Distilled Water. Stir the solution until mixed. Properly label the bottle.

Processing Instructions

Step One: Fix the blood on the surface of the evidence.

Pour enough methanol to cover the item of evidence into a clean, glass tray. Immerse the evidence in the methanol for about one hour. Cover the tray to prevent evaporation. Replenish the methanol in the tray, if necessary. Discard the methanol after use. If the evidence cannot be immersed in methanol, heat the surface with a lamp, heater or oven for at least one hour. Be careful of the risk of fire.

Step Two: Using the working solution

Pour enough working solution to cover the item of evidence into a clean, glass tray. Soak the evidence in the working solution for about two to three minutes or until the latent prints become a blue-black color. If the solution in the tray becomes heavily contaminated, it should be replaced with fresh solution. If the solution is not badly contaminated, it can be poured back into the bottle and used again.

Step Three: First rinse

Pour enough Glacial Acetic Acid-Methanol solution to cover the item of evidence into a clean, glass tray. Immerse the evidence into the solution and rock the tray gently. When excess dye has been removed from the background, take the evidence out of the rinse. If the solution in the tray becomes heavily contaminated, it should be replaced with fresh solution. Discard after use.

Step Four: Second rinse

Pour enough Glacial Acetic Acid-Distilled Water solution to cover the item of evidence into a clean, glass tray. Immerse the evidence into the solution and rock the tray gently for about 30 seconds. If the solution in the tray becomes heavily contaminated, it should be replaced with fresh solution. Discard after use.

Step Five: Drying and Photographing

Allow the evidence to dry at room temperature. Photograph any useful latent prints.

Sequential Processing
Treatment with Physical Developer may be done after Amido Black to try to improve the developed latent prints. It is suggested to photograph any latent prints developed with Amido Black before treating the evidence with Physical Developer.

Photography of latent prints developed with Amido Black should not pose any problems if the surface background is a light color. If the surface is a dark color but will fluoresce, it may be beneficial to use fluorescence examination to enhance the photographic contrast.

Additional Reading

Advances in Fingerprint Technology edited by Dr. Henry Lee and Dr. R. E. Gaensslen
Friction Ridge Skin: Comparison and Identification of Fingerprints by James F. Cowger
Manual of Fingerprint Development Techniques by the British Home Office

Black Powder Processing
13 years ago
By Pat A. Wertheim

This article originally appeared in "Minutiae", The Lightning Powder Co. Newsletter, No. 42, May-June 1997, p. 6.

Although old-fashioned black powder is the workhorse of fingerprint development techniques for crime scene use and is also an important method in the laboratory, maximizing the effectiveness of powder requires far more sophistication than simply dipping a brush into the jar of powder and painting it onto a surface.

More control can be exercised over black powder by working out of a shallow dish. The perfect disposable dish can be made by cutting or tearing a blank inked fingerprint card from any edge into the center of the card. Overlap the two edges of the cut by about an inch (two or three centimeters) and tape the card back together to make the dish. A large laboratory weighing dish may be used, or any other shallow dish or bowl. Place one-half to one teaspoon of powder (approximately one milliliter) into the dish.

Use a quality fiberglass brush (my personal favorite has always been the Zephyr Brush.) Nylon brushes tend to be too stiff and carry too much powder, camel hair brushes are too stiff and cover too small an area, carbon fiber brushes shed loose fibers too easily, and feather dusters tend to carry too little powder (although there are times when less powder is better). Fiberglass brushes work better after a break-in period. But you should never touch the bristles of a brush or allow other residue to contaminate its fibers. Gently grind the powder in the center of the dish using a rotating motion by twirling the brush handle slowly between the thumb and index finger. This action accomplishes two tasks: it breaks up the little balls or clods of powder that result from settling during shipment (these little clods of powder can streak a surface), and it loads the brush fibers with powder.

Before powdering a surface, tap the excess powder from the brush back into the dish. When powdering a vertical surface, place the dish against the surface to catch excess powder falling during the powdering process.

There are two schools of thought on the best method for applying powder: painting and twirling. In the painting method, the brush is swept gently back and forth across the surface. In the twirling method, the brush is twirled between the thumb and index finger. The two methods may be combined and the brush twirled while moving back and forth across the surface. When twirling a quality fiberglass brush, the fibers flare slightly to form a rounded or spherical brushing surface. Only the very center part of this area of the brush should be allowed to gently touch the surface being powdered. When the first hint of a latent fingerprint begins to develop, care should be taken to neither overdevelop nor erase the latent. As much as possible, the brush fibers should be in motion with the flow of the ridges rather than against the ridge flow. For large surface areas such as sliding glass doors or automobile exteriors, I personally prefer to paint the surface until the first traces of a latent print begin to show. Then I twirl the brush very lightly until the latent has sufficient detail to allow for an identification.

A latent should always be photographed or lifted as soon as it is identifiable. Attempting to improve an identifiable latent print prior to photographing or lifting frequently results in destruction rather than improvement. With all of the modern technology available, many people lose sight of the fact that old-fashioned black powder, correctly used, is still one of the most effective methods of fingerprint development. Work from a shallow dish with a quality brush and proper technique, and many good latent prints will result.

Pat A. Wertheim
Director of Training
Forensic Identification Training Seminars, Ltd.

Basic Crime Scene Processing Techniques Using Fluorescent Powders
13 years ago

This article is the tenth in a comprehensive series of articles on latent print development techniques. In this issue, the article is contributed by guest author, Mary Nolte of Melles Griot. Watch for future articles in each issue of Minutić and save these issues in a binder to compile a manual of fingerprint development techniques.

Since the late 1970s, when lasers were first used as an investigative tool to locate fingerprints on "difficult" surfaces, fluorescence-based fingerprint techniques have become increasingly popular. We have all processed items such as guns, plastic bags, Formica counters, and many other surfaces where black or silver powders alone did not produce results. In such situations, the value of fluorescent techniques is well documented. This paper on fluorescent techniques, will discuss the basics of fluorescent powdering techniques at a crime scene.

At a crime scene, we are often limited to using fluorescent powders. This is due to the contamination and/or destruction of property when we use chemical methods. Fluorescent powders not only yield very good results on a variety of surfaces; they are also much less messy than traditional powders.

There are two types of fluorescent powder: magnetic and nonmagnetic. Both work well, however magnetic powders cannot be used on most ferrous surfaces. Personal preference is also a factor in the decision. Nonmagnetic powders include Redwop and Greenwop. Magnetic powders include Blitz Red and Blitz-Green™.

Application of nonmagnetic powders is best done with a feather brush, as minimal powder is needed for adequate coverage. Touch the tips of the feather brush to the powder adhering to the open lid; do not dip the brush into the jar. Application of fluorescent magnetic powders is the same as with standard magnetic powders, using a magnetic applicator.

For Redwop™ or Blitz-Red™, set your forensic light source at any setting from approximately 400nm (violet-blue) to 550nm (green). For Greenwop™ or Blitz-Green™, set your light source anywhere from 350nm (ultraviolet) to 530nm (green-blue). The optimum setting is <530nm as this gives the best intensity. You may want to select another wavelength if background fluorescence is a problem. Select the appropriate color of goggles for the chosen wavelength (orange is used for <530nm). Darken the location as much as possible.

Illuminate the surface while you are brushing on the powder. Care should be taken so as not to over-process the prints. If this should occur, a clean Zephyr® brush can be used to gently clear away excess powder.

Photograph any results using the same color camera filter as the goggles. Fluorescent photography does require longer exposure times, so a tripod is recommended. Make sure you include a scale in the photograph that will be visible in your photos.

While it is possible to lift fluorescent prints, it is good practice to photograph any results prior to attempting to lift. For lifting, it is recommended that you use frosted, non-glare, tape and a black backing card. Mark on the back of the lift card the wavelength that was used to illuminate the fingerprint.

When selecting light source equipment for the crime scene, here are some points to consider:

Weight: A self-contained system will be lightweight and contain all necessary components.

Durability: Rugged exterior to withstand transport and general wear and tear. Internal filter system protects the filters from breakage and contamination For example, an agency ran over their Omniprint™ 1000 with a crime scene vehicle and the unit still functioned flawlessly.

Cross-contamination issues: Smooth cable is easily cleaned and decontaminated. A fan filter will prevent dirt and fibers from entering the unit, preventing cross-contamination of the next scene.

Ease-of-Use: Consider a system with instructions for use, lamp changing, and goggles selection that are permanently affixed to the unit.

High Intensity: For a portable system, a 400W Halide lamp is very good because it offers very high-intensity in the blue spectrum, where the majority of fingerprint work is conducted.

Our thanks to Mary Nolte for sharing her expertise with us. In the next issue of Minutić, Mr. Pat A. Wertheim will write about chemical sequential processing of latent prints.

Enhancement of Latent Prints in Blood
13 years ago

This article is the 12th and final article in a comprehensive series of twelve articles on latent print development techniques written by Pat A. Wertheim. Save these issues of Minutić in a binder to compile a manual of fingerprint development techniques.

Many of the techniques for developing "normal" latent prints do not work suitably on prints in which a significant portion of the latent print residue is blood or blood serum. Therefore, in violent crime scenes or on evidence where blood is present, many examiners choose to use a method specifically formulated to detect bloody prints.

First of all, a very careful visual examination for latent prints must be made using oblique lighting (shining a flashlight flat across the surface), then direct reflected lighting (looking for prints in the glare of reflected light on the surface). Any prints visible under either of these methods should be photographed prior to any development methods.

Next, a fluorescent examination of the surface may be performed for prints with inherent luminescence, followed by photography if prints are found.

For blood-based latent prints which are not visible and cannot be photographed without chemical development, however, several chemical techniques are available.

First of all, Ninhydrin may be applied. Ninhydrin, of course, is an amino acid reagent which will turn the print dark purple. Ninhydrin is more often used on porous surfaces for normal prints. While it does react with blood components, it is not considered the method of choice for blood prints.

More commonly, amido black, a protein dye staining method, is used for bloody prints. For most nonporous surfaces, amido black is prepared in methanol based solutions. A pre-wash of methanol is used to "fix" the print. Then the solution with amido black dye is applied, either by immersing small items or by washing the solution gently over larger items. Finally, rinse solutions are used to clear the background.

Amido black may also be used in aqueous (water based) solutions. While ridge detail generally does not develop as crisply with the aqueous solutions, this option has the advantage of being less hazardous than the methanol solutions and may be used over large areas at scenes of crimes.

A new product on the market is a pre-mixed, one step amido black solution which combines the "fixer" and "developer." While chemical purists may down-play the idea of such a combination solution, the layperson who is uncomfortable with more sophisticated chemistry is still better off using a "one step" method than no method at all.

Another protein stain which works well on blood prints is Coomassie Blue. This method does not require a fixing step prior to staining, and is touted by some as being easier to use and producing less background staining than amido black. Another method mentioned by some is Crowle's staining solution.

It should be noted that any of these chemical methods will prevent subsequent DNA analysis or blood typing. Therefore, if blood typing or DNA are likely to be requested, sufficient samples should be collected for analysis prior to chemical processing for latent prints. If there is no blood present other than the print itself, then a decision must be made whether the latent print would be of more value, or whether the blood analysis is more important.

Some mention has been made outside the scientific literature of the use of luminol as a latent print development technique for bloody prints. However, luminol is used primarily as a technique for visualizing larger patterns of blood and is not recommended for development of fine detail such as that found in a latent fingerprint.

For more lengthy discussions of correct use of blood print development techniques, see the following sources:

  1. Home Office Manual of Fingerprint Development Techniques, 2nd Edition, 1998.
  2. Bodziak, William J., Footwear Impression Evidence, Elsevier Science Publishing Co., Inc., NY., 1990.
  3. Norkus, Paul, and Kevin Noppinger, "New Reagent for the Enhancement of Blood Prints," Identification News, April, 1986, p. 5.
  4. Lightning Powder Company Technical Note No. 1-2742, January, 1999.

This concludes the series on the chemical processing of latent prints written by Pat A. Wertheim. We really appreciate Pat's writing skills in bringing you these technical articles in the past several issues of Minutić. Now that he and his wife, Bonnie, are the owners of Forensic Identification Training Seminars, LLC, he won't have the time to write for us. However, keep looking in the Journal of Forensic Identification for more articles by this talented writer.

Iodine and Silver Nitrate Processes
13 years ago

This article is the sixth in a comprehensive series of articles on latent print development techniques written by Pat A. Wertheim, Director of Training for Forensic IdentiŢcation Training Seminars, Ltd. Watch for future articles in each issue of Minutić and save these issues in a binder to compile a manual of Ţngerprint development techniques.

Two of the earliest chemical methods used to develop latent prints are processing with iodine fumes and treatment with silver nitrate solution. Although both methods have largely been supplanted by more sophisticated chemical techniques, each still has a place in the repertoire of the well-trained latent print technician.

Iodine fumes concentrate in the sebaceous residue of Ţngerprints as a brownish deposit. This method works on both porous and nonporous surfaces. In fact, prior to the discovery of Ninhydrin, iodine fuming was the preferred method of latent print development on paper. Although it is generally considered obsolete today, it still offers the advantage of developing prints without permanently altering or damaging the evidence. However, iodine is listed as both toxic and corrosive, so handling precautions are mandatory to avoid either personal exposure to the crystals or the fumes, or escape of the fumes into the laboratory environment.

Iodine may be used on any surface, but it is most commonly used on porous surfaces. There are several methods of exposing an item to iodine fumes. All involve the use of pure iodine crystals. At temperatures slightly above room temperature, the iodine crystals sublimate. Processing may be accomplished in a fuming cabinet in which a small dish of iodine crystals is placed on a heating device. Typically, such a cabinet is only large enough to hang letter-sized sheets of paper and has a glass window. The evidence is hung in the cabinet, the iodine is place on the heating device, and the cabinet is closed. Prints that develop are photographed immediately. Fixer is available to make the prints permanent, or simply leaving the evidence exposed to air will allow the prints to fade, thus returning the evidence to its unaltered, original state.

As an alternative to a fuming cabinet, a zip-lock bag may be used. A small amount of iodine crystal powder is placed in a bottom corner of the bag. The item (usually a sheet of paper) is placed in the bag and the bag is sealed. The bottom corner of the zip-lock with the crystals inside is held tightly in the palm of the hand to heat the crystals. Prints develop on the paper and can be seen and photographed through the plastic. Care should be taken not to let the paper come in direct contact with the iodine.

Silver nitrate is used on porous surfaces in a solution with distilled water. It is also classiŢed as toxic and corrosive, but does not give off dangerous fumes, as iodine does. A standard silver nitrate solution would contain approximately 3% silver nitrate. For example, three grams of silver nitrate would be dissolved in 100 milliliters of distilled water. While this process works on paper, it ultimately destroys the paper, making Ninhydrin much preferable for use on paper. However, on raw or unŢnished wood, silver nitrate generally performs better than Ninhydrin. Many people prefer Physical Developer over silver nitrate for wood, but Physical Developer only works well on smooth wood where silver nitrate can give good results on smooth and rough wood.

Silver nitrate reacts chemically with the salt (sodium chloride) in Ţngerprint residue, resulting in silver chloride. This silver chloride breaks down under intense light, or with time, to leave elemental silver, which oxidizes to a black or dark brown stain. Unreacted silver nitrate remaining in the wood also breaks down, but at a much slower rate. Therefore, once latent prints develop, they must be photographed while at peak contrast with the background.

Some examiners recommend the use of clearing solutions following silver nitrate processing. Several such solutions are described in Scott's Fingerprint Mechanics.

As a reminder, both iodine and silver nitrate are toxic and corrosive. Protective clothing should be worn, along with nitrile gloves and plastic goggles. With iodine, care should be taken to avoid introduction of the fumes into the lab. Once processed, items should be treated as contaminated to avoid accidental contact with residue remaining on the evidence.

In the next issue of Minutić, Pat will write about Sticky-Side Powder and Gentian Violet processing of tapes.

Magnetic Powder
13 years ago
By Pat A. Wertheim

This article originally appeared in Minutiae, the Lightning Powder Co. Newsletter, #43, July-August 1997.

Even though magnetic powder has been available since the early 1960's, many latent print examiners and crime scene technicians are still not using it to full advantage. Magnetic powder adds a wide range of flexibility to one's resources. In general, magnetic powder is used on nonmagnetic surfaces, and regular powder on iron-based surfaces. However, regular fingerprint powder is inappropriate for some surfaces, including many plastics and textured surfaces, where magnetic powder develops latent prints very well. Textured surfaces such as vinyl imitation-leather or lightly textured automobile dashboards or door panels often respond well to magnetic powder, where regular powder would pack into the low places in the texturing and make development of a good latent impossible. In addition, using the "hot breath" technique, also known as "huffing" works better with magnetic powder than with regular powder.

With magnetic powder, there is no brush with fibers to touch and possibly damage the print. The powder is not itself magnetic, but is attracted by a magnet and carried as whiskers by a magnetic wand. Nothing but the powder itself touches the print. The wand is a closed, hollow tube containing a magnet on a rod. When the rod is pushed in, the magnet is located I the end of the tube and the powder clings to that end. When the rod is pulled out, the magnet is moved to the center of the tube and the powder falls off. With the rod in and a cluster of powder whiskers on the end, you are ready to dust for latent prints.

With regular powder, the more you pass back and forth over the print, the more powder you add to the latent. The opposite is often true of magnetic powder. The first sweep across a surface usually yields as dark a print as you will get. Going back and forth repeatedly will lighten and eventually erase a latent. Therefor, normally, one would stop dusting as soon as a latent appears. However, this characteristic can sometimes be used to advantage. For example, a heavy, greasy print may show up initially as a solid patch, but repeated passes with the wand may actually remove powder from the furrows and yield an identifiable print. This is especially true of greasy prints on car bodies.

Another advantage of magnetic powder is the way in which it lends itself to use with "hot breath." This technique is necessary in dry, desert climates, but may not be needed often in humid areas. When confronted with a "dead print," that is, one from which all of the moisture and oil has evaporate, the print can be temporarily re-humidified by "huffing" breath on it from approximately six inches, then sweeping across it with the magnetic powder before the moisture can completely evaporate. Sweeping across the area too soon can result in a general coating of powder, and the resultant destruction of any latent prints. Likewise, waiting too long can result in complete evaporation of the moisture and no print development. A little practice, however, allows one to effectively use this technique. From day to day and surface to surface, slight modification must be made in the time delay between huffing and dusting, but one learns to modify one's approach quickly as conditions change. The "hot breath" technique is especially useful on plastic bags and similar plastics, and should be tried on any surface where regular powder fails to develop any prints.

In general, magnetic powder is not recommended for surfaces which are themselves attracted to the magnet. However, occasionally magnetic powder will yield a cleaner, crisper print than regular powder. Excess powder may be removed by lightly tapping the object against another surface to dislodge the magnetic particles. Magnetic powder and the "hot breath" technique may also be very productive on a vehicle body following dusting with regular powder. Process the vehicle as usual with regular powder and photograph and lift all latent prints of value. Then reprocess the vehicle in critical areas such as those below the door windows or the roof above the doors, using hot breath and magnetic powder. Frequently, more prints will develop with the magnetic powder than with the regular. Be sure and gently blow off excess powder before photographing or lifting your latent prints.

Ninhydrin Processing
13 years ago
By Pat A. Wertheim

This article originally appeared in Minutiae, the Lightning Powder Co. Newsletter, #45, November-December 1997.

Perhaps the most productive and cost-effective method of developing latent fingerprints on paper is treatment with Ninhydrin. Freshly-mixed Ninhydrin solutions are less expensive and more dependable than premixed aerosol cans or pump spray dispensers. While the premixed containers are ready for instant use when purchased, safety experts today caution against spraying and instead encourage either dipping or painting to apply the solution.

The problem with spraying Ninhydrin solutions is that, even in a fume hood, airborne particles of Ninhydrin dust can form as the carrier evaporates. These microscopic particles may not be effectively removed from the lab by the fume hood, and may find their way back into the air you breathe. Since Ninhydrin reacts with amino acids, any exposure to your body, especially to your eyes or lungs, could have serious results. This potentially dangerous exposure is minimized by dipping or painting.

Protective gear should be worn when using Ninhydrin. Latex gloves are not adequate protection against Ninhydrin solutions. Latex allows some chemicals to pass through and can actually dissolve in other chemicals. Nitrile gloves are recommended as they are more resistant to chemicals, thus offering better protection. Chemical resistant gloves, goggles, breathing mask, and a lab coat should be worn whenever working with Ninhydrin solutions.

If a questioned document examination for handwriting or indented writing is desired, it should always be done prior to a latent print examination. Many of the subtle writing characteristics used by document examiners and any indented writing are lost during chemical processing. In addition, a document examiner may be able to testify that the suspect actually wrote the document, while a latent print examiner can only testify the suspect handled the paper. In the absence of suspects, however, a latent print may yield results through AFIS.

The simplest Ninhydrin solution to prepare is made by pouring 25 grams of Ninhydrin crystals into a gallon (or 4 liters) of solvent. The easiest solvent to obtain is acetone, which is available at any paint store. Methyl Alcohol (methanol) works well, also. The major drawback to these solvents is that they dissolve or run most inks. If the writing itself is important, the document should be photographed and photographed and photocopied prior to chemical treatment.

A more sophisticated solution may be prepared by dissolving 5 grams of Ninhydrin in 75 milliliters of ethyl alcohol (ethanol). To this, add 25 milliliters of ethyl acetate and 3 milliliters of acetic acid. Finally, add this solution to 1 liter of heptane. This formula is more effective on papers with calcium carbonate whiteners in them because it facilitates the reaction by maintaining a slightly acidic environment. The heptane formula is also less apt to run or dissolve inks.

To "dip" the document, choose a clean tray, such as a photographic developer tray, big enough to hold the document lying flat. Put enough Ninhydrin solution in the tray to cover the bottom and simply lay the document in the solution. Remove the item and lay the item in again, other side down. Remove the item again and allow excess solution to run off into the tray. Place the document on a piece of blotter paper or other clean paper to finish drying. Or construct a "clothes line" to hang up the papers inside the fume hood.

To "paint" the document, clamp a clean cotton ball in forceps, dip the cotton ball into the Ninhydrin solution, and dab or paint the document with the wet cotton. Make sure the entire surface is wetted with the solution. Allow the document to dry.

Development of prints may be expedited by application of moist heat. The simplest method of doing that is to hold a steam iron an inch or so above the document and allow the hot steam to lightly waft across the document. Do not apply the iron directly to the paper or allow droplets of water from the iron to contaminate the paper. While steaming will rapidly develop most prints on the paper, it may overdevelop the background and take away from the contrast of the prints. An alternate method is to simply allow several days for the prints to develop without the moist head, constantly monitoring the paper to catch the prints at their peak development and contrast.

Once developed, latent prints should be photographed, as they are prone to fade with time. Fading can be delayed by storing the item in an airtight plastic bag after it is dry and the prints have reached optimum development.

Physical Developer Processing
13 years ago

This article is the ninth in a comprehensive series of articles on latent print development techniques written by Pat A. Wertheim, Director of Training for Forensic Identification Training Seminars, Ltd. Watch for future articles in each issue of Minutiae and save these issues in a binder to compile a manual of fingerprint development techniques.

The chemical process known as Physical Developer (PD) was first used for developing latent fingerprints in the late 1980s and has become more popular as its reputation for developing latent prints on porous surfaces has spread. In many laboratories, it is a standard method on paper (wet or dry), smooth unfinished wood, cardboard, and especially currency. Because PD responds to lipids (oils) in fingerprint residue, it is normally used after Ninhydrin and develops additional latent prints.

PD may be prepared either from pre-mixed kits or by mixing the chemicals from scratch. To work with the fresh chemicals from scratch, three stock solutions must be prepared. Different amounts of these are then combined immediately prior to use. All solutions can be mixed using a magnetic stirrer using scrupulously clean glassware. Beakers, bottles, and glass trays must be thoroughly washed in detergent and water, carefully rinsed, then thoroughly re-rinsed in distilled water. Only distilled water should be used. No metal such as staples or papers clips may be present on items to be processed, nor may metal tongs be used.

To prepare the stock solutions:

Part A (Redox solution): Measure 900 ml of distilled water into a clean beaker. Add and thoroughly dissolve 30 grams of ferric nitrate. Add and dissolve 80 grams of ferrous ammonium sulfate. Add and dissolve 20 grams of citric acid. Store in glass container.

Part B (Detergent solution): Measure one liter of distilled water into a clean glass beaker. Add and dissolve 4 grams of n-dodecylamine acetate. Add and dissolve 4 ml of Synperonic N. Store in clean glass container.

Part C (Silver nitrate solution): Measure 100 ml of distilled water into a clean beaker. Add and dissolve 20 grams of silver nitrate.

In addition to the stock solutions, a pre-wash solution is prepared by dissolving 25 grams of maleic acid in one liter of distilled water. This pre-wash removes calcium carbonate buffers present in most paper which may inhibit the action of the PD.

To prepare the working solution, measure 900 ml of Part A into a clean glass beaker. Add and thoroughly mix in 40 ml of Part B (stir at least five minutes). Add and thoroughly mix in 50 ml of Part C (stir at least five minutes). This working solution is generally good only on the day it is prepared or until the chemicals are exhausted.

Step 1: Rinse the evidence in a clean glass tray of distilled water, gently rocking it for at least five minutes.

Step 2: Pour off the distilled water and add sufficient maleic acid pre-wash solution to cover the evidence, or in a second clean glass tray, submerge the evidence in the pre-wash solution. Gently agitate (rock the tray) for several minutes, or until no bubbles are seen forming on the evidence.

Step 3: Pour off the pre-wash solution and add sufficient PD working solution to cover the evidence, or in another clean glass tray, submerge the evidence in the working solution. Agitate the solution gently and watch closely, removing the evidence when the desired stage of latent print development has been reached.

Step 4: Rinse the evidence thoroughly in a tray under gently running cold tap water for several minutes to flush any remaining chemicals from the paper.

Step 5 (optional): If it is desirable to enhance the image, bathe the evidence briefly in a solution of one part household bleach to three parts distilled water. Following bleaching, the evidence should again be thoroughly rinsed in a tray under running cold tap water.

For those who are intimidated by the chemistry described above or who want to save the time spent ordering chemicals and preparing the various stock solutions, simplified pre-mixed kits are available (without the maleic acid pre-wash). If you wish to mix these solutions yourself, the separate chemicals may be purchased from Fisher Scientific, Sigma Chemical, or VWR, among others. The only known US supplier of one of the components, Synperonic N, is Lightning Powder Company, Inc.

Physical Developer Processing
13 years ago

This article is the ninth in a comprehensive series of articles on latent print development techniques written by Pat A. Wertheim, Director of Training for Forensic Identification Training Seminars, Ltd. Watch for future articles in each issue of Minutiae and save these issues in a binder to compile a manual of fingerprint development techniques.

The chemical process known as Physical Developer (PD) was first used for developing latent fingerprints in the late 1980s and has become more popular as its reputation for developing latent prints on porous surfaces has spread. In many laboratories, it is a standard method on paper (wet or dry), smooth unfinished wood, cardboard, and especially currency. Because PD responds to lipids (oils) in fingerprint residue, it is normally used after Ninhydrin and develops additional latent prints.

PD may be prepared either from pre-mixed kits or by mixing the chemicals from scratch. To work with the fresh chemicals from scratch, three stock solutions must be prepared. Different amounts of these are then combined immediately prior to use. All solutions can be mixed using a magnetic stirrer using scrupulously clean glassware. Beakers, bottles, and glass trays must be thoroughly washed in detergent and water, carefully rinsed, then thoroughly re-rinsed in distilled water. Only distilled water should be used. No metal such as staples or papers clips may be present on items to be processed, nor may metal tongs be used.

To prepare the stock solutions:

Part A (Redox solution): Measure 900 ml of distilled water into a clean beaker. Add and thoroughly dissolve 30 grams of ferric nitrate. Add and dissolve 80 grams of ferrous ammonium sulfate. Add and dissolve 20 grams of citric acid. Store in glass container.

Part B (Detergent solution): Measure one liter of distilled water into a clean glass beaker. Add and dissolve 4 grams of n-dodecylamine acetate. Add and dissolve 4 ml of Synperonic N. Store in clean glass container.

Part C (Silver nitrate solution): Measure 100 ml of distilled water into a clean beaker. Add and dissolve 20 grams of silver nitrate.

In addition to the stock solutions, a pre-wash solution is prepared by dissolving 25 grams of maleic acid in one liter of distilled water. This pre-wash removes calcium carbonate buffers present in most paper which may inhibit the action of the PD.

To prepare the working solution, measure 900 ml of Part A into a clean glass beaker. Add and thoroughly mix in 40 ml of Part B (stir at least five minutes). Add and thoroughly mix in 50 ml of Part C (stir at least five minutes). This working solution is generally good only on the day it is prepared or until the chemicals are exhausted.

Step 1: Rinse the evidence in a clean glass tray of distilled water, gently rocking it for at least five minutes.

Step 2: Pour off the distilled water and add sufficient maleic acid pre-wash solution to cover the evidence, or in a second clean glass tray, submerge the evidence in the pre-wash solution. Gently agitate (rock the tray) for several minutes, or until no bubbles are seen forming on the evidence.

Step 3: Pour off the pre-wash solution and add sufficient PD working solution to cover the evidence, or in another clean glass tray, submerge the evidence in the working solution. Agitate the solution gently and watch closely, removing the evidence when the desired stage of latent print development has been reached.

Step 4: Rinse the evidence thoroughly in a tray under gently running cold tap water for several minutes to flush any remaining chemicals from the paper.

Step 5 (optional): If it is desirable to enhance the image, bathe the evidence briefly in a solution of one part household bleach to three parts distilled water. Following bleaching, the evidence should again be thoroughly rinsed in a tray under running cold tap water.

For those who are intimidated by the chemistry described above or who want to save the time spent ordering chemicals and preparing the various stock solutions, simplified pre-mixed kits are available (without the maleic acid pre-wash). If you wish to mix these solutions yourself, the separate chemicals may be purchased from Fisher Scientific, Sigma Chemical, or VWR, among others. The only known US supplier of one of the components, Synperonic N, is Lightning Powder Company, Inc.

Instructions for Rubber-Gelatin Lifters
13 years ago

These rubber-gelatin lifters are especially developed for the lifting of fingerprints, footprints, dustmarks and micro traces. The thick, non-aggressive, low-adhesive gelatin layer permits the lifting of traces from almost every surface, including porous materials, such as paper or cardboard. Lifted prints can be collected for photography or closer examination. The lifters consist of three layers: the Carrier, the Adhesive and the Cover Sheet (figure one). There are three kinds of lifters: Black lifters, White lifters and Transparent lifters.

The black and the white lifters have a carrier of linen rubber. The transparent lifters have a clear polyester film as a carrier. All lifters are protected by a transparent polyester Film. Black and white lifters can easily be marked since the white linen rubber backing can be written on. The transparent lifters have non-sticking paper edges for marking and easy lifting of the cover sheet. The lifters can easily be cut with scissors to fit a particular job. Do not remove the cover sheet before cutting (Figure two).

Lifted prints or marks can easily be photographed after removal of the cover sheet. When the prints have been photographed the cover sheet can be replaced (after careful cleaning to remove any possible contamination).

Powdered Fingerprints can always be lifted with rubber-gelatin lifters. Which kind of lifter should be used depends on the color of the powder and personal preference. With silver or gray powder, for instance, the black lifters can be used to improve contrast. It should be remembered that with white and black lifters a negative image of the fingerprint is obtained.

Photography is then necessary to obtain the positive image. With the transparent lifters, a positive image can be obtained directly by photographing them through the transparent backing. To lift a powdered print, cut a section large enough to cover the area. It is recommended to cut off or notch a small corner of the lifter (Figure three).

There are two reasons for this. The first reason is that after lifting, the notched cover sheet can easily be replaced exactly over the lifter. The second reason is that if the lifter is always used in the same way, for instance with the notched edge on the right hand top side while lifting, the orientation of the lifted print can always be reconstructed. Before lifting the print, the cover sheet has to be removed (Figure four) and put aside, upside down (to avoid contamination).

The safest and only recommended method for placing the lifter on the print is described in the next paragraph. Adhere an edge of the lifter next to the developed print. The upwardly slanted lifter is now carefully smoothed down, while rubbing with a thumb, so that no air bubbles are locked in (Figure five). After that, the lifter is smoothed over the whole surface. Subsequently, the lifter is picked up, beginning at one of the corners. Then put the lifter (gelatin layer up) on a flat horizontal surface to replace the cover sheet. For small prints this can be done analogous to the lifting procedure described above (Figure six). For larger prints (e.g., palm prints), a roller is very convenient (Figure seven). Trapping of air bubbles will result in the creation of shallow craters, which will not destroy the print, but may cause problems in photography. Lifted dusted prints will fade, and ultimately disappear in time. Fading will be noticeable after days or weeks, depending on the storage temperature (the lower the better). Prints developed with silver powders, on the other hand, are known to have been stored for several years without apparent fading. It is recommended though, to photograph prints as soon as possible.

13 years ago
     To be continued......
13 years ago

Splicing a Print
In case too much powder has been used, and the Fingerprint ridge detail is filled in, improvement of the print may be possible by the so-called Splicing of the print In splicing, two pieces of the same size lifter are used. First, the print is lifted as described above, and the cover sheet replaced. (Replacement of the cover sheet is essential, as will be clear in the following description.) Then the cover sheet is removed again. Due to the presence of excess powder, a copy of the print will be visible on the cover sheet. This copy can be transferred to the second piece of lifter by switching the covers. That is, the cover sheet of lifter #1 is put on lifter #2, and vice versa. In many cases this procedure will also improve the print on lifter #1 as well. Splicing can be advantageous in another way. When dirt or dust from the surface has been picked up during lifting, the dirt will remain on lifter #1 and the print is transferred to clean lifter #2, so that an undisturbed print is obtained. Note: There seems to be a controversy about the ethics of this technique. Some experts, therefore, prefer to use double lifting of a print (described in the next paragraph) when splicing seems advantageous.

Double Lifting
Often, a latent print can be lifted twice with only one application of latent print powder. The second lift will, in many cases be much clearer, but with less contrast. Another possibility is lifting for a second time after an additional application of powder. Of course, no rules can be given for these techniques, as much depends on experience. It is recommended though to try it for latent Fingerprints on aluminum.

Improvement of Older Prints
Fingerprints on objects which have been standing in sunlight or outside for longer periods are difficult to visualize. Because all of the water is evaporated from the print, hardly any powder adheres to it. By attaching a piece of lifter to it for some minutes, the print can be rehumidified. Subsequently, the print can be dusted in the usual way and lifted with a fresh piece of lifter. Before performing this technique, be sure that the objects have cooled.

     Stay tuned for part three....
13 years ago

Footwear Impression in Dust
In dust, the sole of a shoe acts like a stamper, leaving an invisible or hardly visible print. Shoeprints can be lifted from all smooth and hard surfaces, such as floor coverings, painted wood, paper, tabletops, etc., with rubber-gelatin lifters. For lifting shoeprints in dust, the large black lifters are commonly used. Dustprints not visible to the naked eye can be searched for in two ways. Either the prints are First discovered with the aid of a Floodlight, Forensic Light Source or Flashlight, and then lifted, or the whole area where prints are suspected is covered with lifters. If the whole area is covered with lifters, reconstruction of the pattern is aided by drawing stripes over the seams of the lifters and numbering them. It may be advantageous to leave the lifters on the surface for some minutes, to fully adhere to the dustprint. Even if the shoeprints did not show up on lighting the surface and were not visible upon lifting, they may show up under oblique lighting of the lifter surface in a dark room (after removing the cover sheet). Lifters with no apparent prints in normal light, may now show a highly detailed image. After photography, the cover sheet can be replaced after careful cleaning. For replacement of the cover sheet on these large lifters, without trapping air bubbles, a large roller is very convenient (Figure seven). Shoeprints made visible with Fingerprint powder can also be lifted with rubber-gelatin lifters. WARNING: Avoid contamination of the lifters after having removed the cover sheet. It is recommended to wear dust-free clothing during handling and photographing of the lifters.

Longevity of Latent Shoeprints
Lifted shoeprints (dustmarks) may slowly fade in time. For very weak prints this may be noticeable after storing for a few days. This will depend on temperature. The lower the temperature, the slower the fading. This, however, should not be a concern, since lifted shoeprints can easily be photographed after removing the cover sheet. Oblique lighting will show details not visible before photography. So far, no materials are known to us that faded on the lifter surface before satisfying photographs had been taken. When shoeprints contain very coarse material, e.g., sand, problems is expected in replacing the cover sheet. Around the coarse particles, small air bubbles will be present. When too many are present, the cover sheet will not sufficiently be adhered to the lifter. Several measures can be taken to avoid these problems. First of all, it is recommended to photograph the shoeprint before lifting. Second, the lifted print can be photographed at the crime scene before the cover sheet is replaced. Third, instead of replacing the cover sheet, the lifter can be put in a clean box (e.g., a photo-paper box) and taped to the bottom. Fourth, the cover sheet can be secured to the lifter with staples or adhesive tape, to prevent movement in which the coarse particles might destroy characteristic details.

Paint Traces
When paint left on a vehicle by a hit-and-run accident has to be collected for examination, the white lifters can be used. After removing the cover sheet, one edge of the lifter is attached to the surface of the vehicle, directly under the spot with the paint to be removed. Then, the paint is scraped off carefully with a scalpel. The removed material will fall in the gap between the lifter and the surface of the vehicle, or on the lifter itself. When enough material has been removed, the lifter is pressed to the surface of the vehicle. This way, all loose particles will be picked up by the lifter. The lifter can be removed and the cover sheet replaced. If necessary, the cover can be secured with staples or adhesive tape.

Sampling of Micro Traces
Due to the non-aggressive nature of the lifter, micro traces and hairs can be collected without fear of damaging the sampled material. When it is necessary to remove micro traces from the lifter, the low tack enables removal by using a scalpel or pair of tweezers. Collection of hair is done with white lifters. If an area is to be searched for micro traces, it is recommended to divide the area in squares (e.g., 20 x 20 cm or about 8 x 8 in.) and to use a fresh piece of lifter for each square. The size of the lifter is actually dictated by the amount of contamination in the area to be investigated, since sampling of dirt or large amounts of micro traces will result in quick loss of tack. A piece of 8 x 8 cm (about 3 x 3 in.) usually suffices.

Sequential Processing of Latent Prints
12 years ago

This article is the 11th in a comprehensive series of twelve articles on latent print development techniques written by Pat A. Wertheim. Save these issues of Minutić in a binder to compile a manual of fingerprint development techniques.

For many surfaces, there are several methods for developing latent prints, each of which reacts with a different component of the fingerprint residue. Frequently, it is desirable to go to extra lengths and use more than one method to locate latent prints in an important case. However, the use of one method may ruin subsequent chances of locating latent prints with other methods.

"Sequential Processing" is the use of two or more methods in a sequence designed so that each technique used avoids the destruction of fingerprint residue for subsequent methods. Two common surfaces will be discussed with a detailed sequence of several methods for each surface.

Perhaps the most common type of surface examined for latent prints is the smooth, nonporous, nonferrous surface such as glass, painted surfaces, and some hard plastics. The first step should be a close and careful visual examination of the surface for latent prints. This step could include the use of a flashlight for side lighting. It might also use the "hot breath" technique, or "huffing" to fog the surface. Any prints visually observed should be photographed before proceeding to the next step.

The second step should be an examination with a Forensic Light Source, including photography of any prints visible through inherent luminescence. Following this preliminary fluorescent examination, the surface should be "super-glue" fumed. Again, a visual examination and photography should be used before proceeding.

The next step would be to lightly dust the surface, first using nonmagnetic powder (then photographing any prints, then lifting them), followed by powdering with magnetic powder using the "hot breath" technique (then photographing any addition prints, then lifting them). Fluorescent powders may be substituted for the more traditional nonmagnetic or magnetic powders, or may be used in addition to the others.

Finally, dye staining with a suitable fluorescent dye should be done last, again followed by photography. By using all of these methods correctly and in the proper order, one could be reasonably confident of recovering any latent prints of value on the surface. Probably the second most common type of surface examined for latent prints is a porous surface such as paper or cardboard. Again, the first step should be a careful visual examination with photographs taken of any visible latent prints. Next, a fluorescent examination should be made for inherent luminescence, again accompanied by photography of any prints observed.

The next step should be iodine fuming. Although generally considered relatively unproductive, iodine fuming offers the advantage of temporarily making the prints visible without permanently altering the evidence. Any prints developed should again be photographed before proceeding. Next, magnetic powder may be used, although this is normally effective and should only be tried on very fresh latent prints. Again, prints should be photographed.

Following these methods, various liquid chemicals would be used. First, DFO would be applied, followed by a fluorescent examination and photography. Then, traditional Ninhydrin would be used, followed by photography. Finally, Physical Developer would be used. At this step, Physical Developer still frequently develops latent prints completely undetected by all of the previous methods. (The previously recommended silver nitrate method has been replaced by the more effective Physical Developer.)

Other common surface types include smooth, nonporous, ferrous surfaces; plastic films; raw wood; adhesives; waxed surfaces; and textured nonporous surfaces. For a detailed discussion of these surfaces and other less common surfaces, see the Home Office Manual of Fingerprint Development Techniques (1st edition: 1986 or 2nd edition: 1998) or the Home Office Scenes of Crime Handbook of Fingerprint Development Techniques (1st edition: 1988 or 2nd edition: 1993). For a set of simple flow charts of these methods, see Section one of the Lightning Powder Company printed product catalog.

In the next issue of Minutić, Pat will write about enhancement and development of latent prints in blood, the last article in the series.

Small Particle Reagent
12 years ago
By Pat A. Wertheim

This article originally appeared in Minutiae, the Lightning Powder Company newsletter, No. 49, July- Aug. 1998.

Prior to the discovery of molybdenum disulfide (MoS2) in suspension as a latent print development agent, latent prints on wet, nonporous surfaces were virtually impossible to recover. Latent prints containing oily or sebaceous material can now be developed dependably on wet surfaces using a suspension known as " Small Particle Reagent" or " SPR" for short.

In a latent fingerprint on a wet surface or one submerged under water, the oily components of the fingerprint residue are held in place by the surface tension of the water. As long as the latent remains wet, the oils retain the shape and details of the fingerprint. However, when the surface is exposed to air and the water drains off or evaporates, the oily residue tends to spread out or run, resulting in a smudged print. Processing with "SPR" before the surface dries will develop and fix the print.

SPR is prepared by mixing approximately an ounce of MoS2 powder in a quart of water. In metric measurements, one would measure around 30 grams of MoS2 per liter of water. In either case, two or three drops of laboratory detergent is added. A good detergent is PhotoFlo. The detergent should be used sparingly, however; too little and the MoS2 will fog the background, too much and the detergent itself will degrade the latent. Normally, the MoS2 and detergent are placed in water in a bottle or jar with a watertight lid, and shaken vigorously to create the suspension. It should look like dirty used motor oil when it is ready to use.

It has been reported that adjusting the pH of the suspension to somewhere between 3 and 4 by the addition of acetic acid increases the effectiveness of the SPR. If you want to try this, mix the suspension first, then add a few drops of acetic acid. Monitor the pH with test paper until the correct range is established.

The SPR suspension must be continuously agitated during use, usually by shaking the bottle from which it is being dispensed. The word "suspension" refers to particles of insoluble material mixed into the water, but not dissolved in it. The word "solution" would refer to a material which actually dissolves in the water.

SPR is normally sprayed on the wet surface being examined for latent prints. For example, if a vehicle were submerged in a lake and there was a request for a latent print examination, SPR could be sprayed onto wet vehicle body and glass surfaces as it was being removed from the lake. After the SPR is sprayed onto the surface, it must be rinsed off with clean water before it begins to dry. All that remains after rinsing is the MoS2 which has adhered to the latent print. The latent may then be photographed and, after it has dried, lifted in normal fashion.

Smaller items may be processed using the SPR in a tray. The items should be submerged in SPR with the side to be processed facing up, then removed and rinsed under clean water. As with SPR in a spray bottle, the suspension must be agitated or stirred frequently to ensure the MoS2 remains in suspension and does not sink to the bottom of the tray.

SPR can also be used successfully where foreign residue would prevent the use of dry powder, such as a soft drink can coated with sticky droplets of the beverage, or on a bar top with spilled drinks on it.

Experiments by the Israel National Police have also found SPR effective at arson scenes in developing latent prints from glass fragments coated with accelerant, even after burning. For a detailed discussion of their tests, see The Journal of Forensic Identification, Vol. 46, No. 5 (Sept./Oct. 1996).

Although the Home Office, in its Scene of Crime Handbook of Fingerprint Development Techniques, says that MoS2 presents no known hazards, molybdenum and its compounds are listed by others as being toxic. Therefore, precautions are recommended in the use of SPR. Read the MSDS on the product. Wear gloves and a dust mask when mixing the MoS2, and again when spraying the SPR. The compound is extremely messy, as well, and clean up may be necessary after use. Soap and water are normally sufficient to clean the residue left by SPR.

Atmospheric Superglue Method
12 years ago
By Pat A. Wertheim

This article originally appeared in Minutiae, the Lightning Powder Co. Newsletter, #44, Sep-Oct 1997.

Some latent print technicians believe superglue should be listed second only to powder as the most effective latent print development technique. Others believe it should come first. Either way, no one can deny that superglue fuming is the most revolutionary new method to be discovered since the invention of powder. Superglue fuming works on many surfaces where powder is ineffective, such as plastics, and has the advantage of fixing the print on the surface for later presentation in court.

First, you need a more or less airtight container to hold the evidence. Three elements are necessary inside the chamber: superglue fumes, humidity and warmth. For a chamber, I regularly use a large coffee can for small items such as a handgun or a baggie of dope. An aquarium is an ideal medium-size chamber. For a large chamber, an old refrigerator body with removable wire shelves is excellent. I have also used cardboard boxes (with the seams taped) and plastic garbage bags (blown up loosely like a balloon, then closed with a wire twist).

For humidity inside the chamber, you first need to analyze the humidity outside the chamber and the temperature of the surroundings. If you are in a warm location with high humidity, you probably do not need to add any moisture to the chamber in order to get good results. If the humidity in your area is low or the temperature is cold, a glass of hot tap water works well in a small chamber, while a tray (such as a photo developing tray) of hot tap water works well in a large chamber. In a coffee can, a long huff of breath adds plenty of moisture. Be careful not to put very cold evidence into a warm, humid chamber, as condensation may damage latent prints. Allow cold evidence to warm up before placing it into a chamber.

For warmth, again analyze your surroundings. In a warm climate, perhaps no warming device is necessary for the chamber. The best results seem to occur at about 100 degrees Fahrenheit with 80% humidity. In a large chamber, such as an old refrigerator body, one or two 200-watt light bulbs will raise the temperature to a good range, even on a cold day. Cheap ceramic light fixtures mounted into the floor of the refrigerator are perfect. Run the electrical cord out the door, and the rubber gasket will seal around the cord when you close the door. Then you can simply plug the cord in to turn on the lights.

Introducing the superglue fumes into the chamber is the last step. Some technicians prefer the glue packets which peel apart like Polaroid film. Some prefer plain liquid glue. In the coffee can, drip 10 or 12 drops around the side of the can near the top. Place the evidence in the can, being careful not to allow it to become glued to the can. Finally, huff some breath into the can as you gently snap the lid down. Five or ten minutes should be sufficient time. In a 5 gallon aquarium, I would use 10 to 12 drops of glue in a small aluminum dish, either on a hot plate or floating in hot water (do not allow water to get into the glue, or vice versa, as that will restrict the fuming action). In a larger chamber, calculate the amount of glue at the rate of one-ounce (28 g) per 100 cubic feet of container volume. Again, a hot plate helps evaporate the glue. If you are using light bulbs mounted on the floor to heat the chamber, you can construct a grill immediately above the top of the light bulb, even in contact with it, and place the small pan of glue directly over the light bulb to evaporate the glue. In containers larger than the coffee can, I generally use about 30 minutes fuming time.

The Home Office at Scotland Yard rates superglue fumes as nontoxic, but irritating. The fumes should be vented away from you, or the container should be placed in a fume hood or other location that allows good ventilation, such as an outdoor shed or carport. Some people are able to open the chamber within the office and it doesn't bother them. This is not the best recommended method. Please read the MSDS for the properties of superglue. If you accidentally glue skin to skin, or get superglue in your eyes, get immediate medical attention.

The best way to learn how to use glue effectively is to experiment. It is a simple, dependable process. It even makes a great science fair project for student in school. For the cost of a tube of superglue from the grocery store, and an old coffee can, your elementary or junior-high age children can construct a fantastic science experiment which will be a guaranteed attention-getter at the school science fair. You can achieve even more impressive results in the lab with a little effort and practice.

The Cyanoacrylate Fuming Method
12 years ago

There is little need to mention the importance of obtaining fingerprints in criminal investigations. Fingerprints have long been considered one of the most valuable types of physical evidence that can be found at a crime scene.

The cyanoacrylate fuming method (often called the super glue method) of developing latent fingerprints has proven to be an effective tool for professional investigators, and the quality of its results has made it a popular one. Any agency that works with latent fingerprints and does not already use the cyanoacrylate fuming method should seriously consider adopting it.

The super glue method was first employed by the Criminal Identification Division of the Japanese National Police Agency in 1978. Shortly thereafter, it was brought to the United States by the United States Army Criminal Investigation and Bureau of Alcohol, Tobacco, and Firearms Laboratories. It is currently used in most state and metropolitan police forces across the country.

To understand how the super glue method works, one must first know some basic information about fingerprints themselves. There are three different types of fingerprints: visible, impression, and latent. Investigators normally need a portable, permanent copy of the fingerprints. A photograph can generally fulfill this need. Of the three types of fingerprints, visible fingerprints can be photographed directly, and impression fingerprints can usually be photographed under special lighting conditions. It is only the invisible latent fingerprints that are difficult to photograph. They must first be made visible.

There are three general groups of techniques for making latent fingerprints visible, and virtually every known method can be categorized into one of the three groups or a combination of the three. The three groups consist of the physical techniques, the chemical techniques, and the instrumental techniques. Cyanoacrylate fuming is a chemical technique.

Latent fingerprints are composed of several chemicals exuded through the pores in the fingertips and are left on virtually every object touched. The primary component of latent fingerprints is ordinary sweat. Sweat is mostly water, and will dry after a fairly short period of time. The other components of latent fingerprints are primarily solid, however, and can remain on a surface for a much longer period of time. These other components include organic compounds like amino acids, glucose, lactic acid, peptides, ammonia, riboflavin, and isoagglutinogens as well as inorganic chemicals like potassium, sodium, carbon trioxide, and chlorine.

The basic concept behind all of the chemical techniques is to apply something that will chemically react with one of the constituent chemicals of latent fingerprints to the area suspected of containing such a fingerprint. The resulting reaction will give all present latent fingerprints a new chemical composition. This new chemical composition will make the latent fingerprints easily rendered visible, and they can then be photographed.

The super glue method is no exception to this rule. Most liquid super glues are really either methylcyanoacrylate or ethylcyanoacrylate. Less common types of super glue include butylcyanoacrylate and isobutylcyanoacrylate. Fortunately, all these types of super glue are nearly identical physically and chemically. Super glue reacts with the traces of amino acids, fatty acids, and proteins in the latent fingerprint and the moisture in the air to produce a visible, sticky white material that forms along the ridges of the fingerprint. The final result is an image of the entire latent fingerprint. This image can be photographed directly, or after further enhancement.

To enable such a reaction to take place, the cyanoacrylate must be in its gaseous form. The basic procedure to develop latent fingerprints using super glue takes this fact into account, but is still not overly complicated. The surfaces that are to be checked for latent fingerprints are placed in an airtight tank along with a small heater. A few drops of liquid super glue are placed into a tiny, open container, and the container is placed on top of the heater inside the tank.

12 years ago
The tank is then carefully sealed, and the heater activated. According to Lee and Gaensslen, the boiling point for most super glue varies between forty-nine and sixty-five degrees celcius (roughly one-hundred twenty to one-hundred fifty degrees fahrenheit) depending upon its exact chemical composition1. 2, use two. The three most common acceleration methods are the fume circulation method, the chemical acceleration method, and the water vapor method.

The fume circulation method is fairly straightforward in principle; if the cyanoacrylate fumes are actively circulated around the tank, the air inside will have a constant concentration of them and all latent fingerprints in the tank will be in constant contact with some cyanoacrylate. In practice, the fumes can be forced to circulate by the strategic use of a couple of electric fans inside the tank.

The chemical acceleration method is quite different from the other acceleration methods. Instead of being an addition to the basic procedure, the chemical acceleration method is a replacement for part of it. When the chemical acceleration method is used, the heater is discarded and a chemical like sodium hydroxide is placed in contact with the super glue. This chemical will cause the super glue to produce cyanoacrylate fumes, and the reaction will then proceed normally.

The water vapor method is extremly simple in theory and in practice. Since the reaction requires moisture from the air to occur, the air in the tank can be kept at a high level of humidity to ensure that there will always be enough moisture for the reaction to take place. The humidity in the tank can be kept high simply by placing an open container of water inside the tank.

Regardless of whether or not an acceleration method was used, the final image of the fingerprint is not always easy to photograph. Since the chemical deposits left by the reaction are white, there may not be enough contrast for an effective photograph to be taken if the surface they are on is also white.

If this is the case, a simple method exists that solves the problem. This is the technique of dusting. Different colored dusts may be brushed onto the image of the fingerprint, and they will cling to the sticky white chemical from which it is formed, effectively changing its color. The super glue technique produces outstanding results on all non-porous surfaces like metal, glass, and plastic; it will sometimes work on porous surfaces too, but not as well.

Overall, the super glue technique is an excellent means of developing latent fingerprints. It stands as one of the best methods of obtaining one of the most important types of physical evidence. It can be highly recommended to any agency that has not already adopted it as a primary method of developing latent fingerprints.

Latent Prints in Dust
12 years ago
by Captain Curtis C. Frame,
Criminal Investigation Division
Jasper County Sheriff's Office
Jasper, Texas
Article Copyright © 2000, Curtis C. Frame

A Latent print found in dust, may be the only clue in which there are no other leads. And because the areas that are routinely touched by the victims are not normally dusty, the dust print we find may be the only link we have of the perpetrator to the crime scene. However, most crime scene and latent print examiner experts will say that, regardless of their importance, latent prints in dust are a nightmare. This is due to the fact that a latent print in dust was actually left there due to the dust being removed by adhering to the ridges of the skin that touched it.

So, in order to avoid having to reverse the negatives or use a liquid lifter, I've been working with my colleague in hopes of finding an easier, simpler method of obtaining these extremely important latents. And after a lot of time, effort, and countless experiments, I think we've found a solution.

To remove a Latent print in dust, simply place a clear piece of wide fingerprint tape over the print, and apply with very slight pressure. After lifting the tape from the surface, you can hold the tape in front of a light source and see the lifted latent dust print. (Please Note: The friction skin ridges will not be seen as well as the friction skin furrows. The dark lines that you see will be the dust not taken from the surface by the friction skin ridges, but that which was left behind by the friction skin furrows.) Then you will place the tape (sticky side down) over the top of an ordinary styrofoam cup. Because you have used the wide tape, the print will be sealed and well preserved, without fear of damage or contamination, inside the styrofoam cup.

The remaining process is also relatively simple. When you are ready to proceed with the examination of the print that you lifted, simply cut the bottom of the styrofoam cup off, and discard. Then place a black card or black sheet of construction paper, on the bottom of the upper half of the styrofoam cup. This will create a black background for your print. Now place under a camera with direct lighting. The inside of the white styrofoam cup will create bounce lighting, which will help to balance the light for your photograph. You may need to "play" with the lighting and/or the exposure, just as you would any other latent photography, in order to achieve the best picture.

By using Black and White film, and black background, the pictures, when developed, will produce a latent dust print with the black lines being a representation of the friction skin ridges. The white lines of the print will be due to the dust that was left by the friction skin furrows, being adhered to the fingerprint tape. Again, I repeat, the photograph of the Latent dust print, using this method, will show black ridges, and white furrows.

After you have finished photographing your Latent dust print, simply preserve the print by placing it (cup, and all) inside another styrofoam cup, and seal with tape.

Please be very careful when lifting a Latent dust print from its surface. There is no such thing as a "second" lift. You may want to practice on a Latent dust print of your own, in order to achieve the best pressure of tape application, as well as the best picture, when you photograph your print in the styrofoam cup.

Latent Prints in Dust

Left photo:
This is a latent print in dust as it appears on an item before it is lifted with the clear tape and placed on the top of the styrofoam cup.

Middle photo:
This is a photo of the latent print after it has been lifted (as in photo on left) and placed on the styrofoam cup. This view is looking from the top, into the cup with a black background behind the print (below the "cut-off" portion of the styrofoam cup).

Right photo:
This is a photo of a known inked print.

NOTE: Both the latent and the known print in these photos were found to be a match

Hidden Evidence: Latent Prints on Human Skin
12 years ago
By Ivan Ross Futrell

Mr. Futrell is a supervisory fingerprint specialist in the Latent Fingerprint Section of the FBI Laboratory in Washington, D.C.

This Article Originally Appeared in the FBI Law Enforcement Bulletin, April 1996.

(Recent research proves that identifiable prints can be obtained from the skin of homicide victims under real field conditions, not just in the laboratory.)

Whether to stop them from fleeing, immobilize them, or dispose of them, murderers often grab their victims. What homicide detective has not wished for the ability to develop identifiable fingerprints of a suspect from the skin of a dead body? Crucial fingerprint evidence linking the perpetrator to the victim must be right there, but, until recently, attempts to retrieve those prints rarely met with success.

Skin possesses a number of unique qualities that distinguish it from other specimens examined for latent prints. Skin tissue grows and constantly renews itself, shedding old cells that might contain the imprint of an assailant's grip. Its pliability allows movement and, hence, possible distortion of fingerprints. As the skin regulates the body's temperature and excretes waste matter through perspiration, latent prints can be washed away.

In addition to these natural changes, the skin of homicide victims often is subjected to many harsh conditions, such as mutilation, bodily fluids, the weather, and decomposition after death. Further, during crime scene processing, many people might handle a body while removing it from the scene, which also can destroy existing fingerprints or possibly add new ones to the corpse's skin.

In spite of these hurdles, research conducted by the FBI Laboratory's Latent Fingerprint Section--in conjunction with police and medical authorities in Knoxville, Tennessee--proves that latent fingerprints can be lifted from skin if only investigators are willing to try. This article outlines the history and research that led to development of a workable method for developing identifiable latent prints on human skin.


The FBI has been involved in research on methods to develop identifiable latent prints on human skin for many years. In the early 1970s, FBI scientists reexamined existing methods using cadavers at a major university and the Virginia State Medical Examiner's Office in Richmond, Virginia. Most of these cadavers had been embalmed.

To create prints, these researchers applied a coating of baby oil and petroleum jelly to their hands and then touched areas of skin on the cadavers. At timed intervals, they then attempted to develop these latent prints, using primarily the iodine/silver transfer method. This method has five steps: heating iodine in an iodine fuming gun, directing the fumes onto the skin, laying a thin sheet of silver on the skin, removing the silver plate and, finally, exposing the plate to a strong light, which causes the prints to become visible.

The researchers developed identifiable prints in this fashion within a time frame that ranged from several hours up to several days after the prints were applied. It should be noted, however, that the researchers achieved these results under ideal laboratory conditions. It was not surprising that they developed latent prints composed of artificially introduced oily substances on embalmed cadavers. Yet, those early efforts provided important background data for subsequent research conducted in Tennessee.

In 1991, a police specialist from the Knoxville, Tennessee, Police Department contacted the FBI Latent Fingerprint Section to inquire about the FBI's experience and previous research on developing latent prints on skin. His own examination of numerous homicide victims had not produced prints with identifiable ridge detail, even though some cadavers exhibited observable outlines of fingers and palms. Out of these discussions arose a joint research project involving the Knoxville Police Department, the University of Tennessee Hospital, the Department of Anthropology at the University of Tennessee, and the FBI.

To develop a consistent and reliable technique for developing latent prints on skin, the researchers established a protocol significantly different from previous efforts. They decided to use only unembalmed cadavers and to place latent prints composed of only natural perspiration and sebaceous (oily) material. They felt that such conditions more accurately replicated field conditions faced by police investigators.

12 years ago

The researchers first examined the body of a 62-year-old white female who had been dead for 9 days. Areas of skin were sectioned into numbered squares drawn on the body. One researcher placed latent prints on the skin by wiping his hand across his brow or through his hair and then touching the cadaver. The researchers then tried to develop the latent prints at timed intervals by employing several methods, including the use of lasers, alternate light sources, iodine/silver transfer, cyanoacrylate fuming (commonly referred to as "glue fuming"), regular and fluorescent powders, specially formulated powders, regular and fluorescent magnetic powders, liquid iodine, RAM, ardrox, and thenoyl europium chelate.1

Most of these methods developed the latent prints up to approximately 1 hour after the prints had been deposited. For additional documentation, during the next several days, researchers tested the techniques on other cadavers, but most methods failed to provide consistent results.

The one technique that developed identifiable latent prints most often was glue fuming in conjunction with regular magnetic fingerprint powder. Similar to iodine/silver transfer, this method involves heating glue and directing the fumes onto the skin, then applying fingerprint powder to reveal the latent prints.

To test this technique further, researchers glue fumed several areas of skin containing sebaceous latent prints 2 hours after depositing the prints. Sixteen hours later, they applied various fingerprint powders to those areas. Using a fluorescent powder specially formulated for this testing, they developed a latent print of value for identification purposes. Initially, the researchers believed that the special fluorescent powder provided the key to obtaining usable prints, but additional tests proved that the type of powder did not matter as much as the amount of time allowed for glue fuming.

Glue Fuming Device

As they continued their research, the scientists realized that they needed an improved method for spreading glue fumes over the skin. The earlier method used--forming an airtight plastic tent over a small area of skin or over an entire body--did not always work. It was impossible to distribute glue fumes evenly over the skin and extremely difficult to confine all of the fumes to the tent. In addition, when they removed the plastic tent at the end of the fuming process, the fumes often forced the researchers out of the work area. To alleviate these problems, one of the researchers, the police specialist from the Knoxville Department, developed a portable glue fuming chamber.

The glue fuming chamber contains a built-in heat source and a small electric fan. Glue is poured into a small disposable preheated aluminum pan and placed in the chamber. After approximately 5 minutes, the fan is turned on and the glue fumes flow out through a plastic hose attached to the top of the chamber. When set at maximum, the amount of fumes forced through the hose approximates the exhaust from an automobile on a cold day. This device enables the user to control the amount and time of the glue fuming much more easily than the tent method.

Using the new device, the scientists tested squares of skin to determine the optimal fuming time. They tried fuming in increments from 5 seconds up to 2 minutes. They obtained identifiable latent prints most often when glue fumes had been applied to the skin for 10 to 15 seconds.


In the early testing, it seemed that particular types and brands of fingerprint powders provided the best results. As the research progressed, however, it became apparent that this was not the case. More than 30 brands and several types of powders and applicators were tested. In the end, researchers determined that powder selection is less critical than ensuring that the glue fuming process is performed correctly.

Both fluorescent powders and regular magnetic powders produce identifiable prints. With non-magnetic fluorescent powders, the best results are obtained by applying the powder with a feather duster rather than a conventional brush, which generally holds more powder. Too much fluorescent powder tends to overwhelm the latent print and the background. While fluorescent powders work, they do have some drawbacks. They generally cost more than regular magnetic powders, are more difficult to see, and require special light sources, filters, and additional photographic knowledge.

12 years ago

In comparison, regular black magnetic powders produce useful prints and cost much less. They also do not require special photographic skills. Indeed, technology does not need to be complex or costly in order to be effective.

Field Conditions

Developing latent prints under ideal laboratory conditions proved that prints could be obtained from human skin, but the researchers wanted to make sure that practitioners in the field could obtain similar results. In real life, homicide victims might not be found immediately, bodies might be exposed to the elements or other harsh conditions, or they might be taken to the morgue and refrigerated before they can be examined for prints.

To ensure that the process would work, the researchers simulated field conditions by testing cadavers that had been exposed to the elements for several days, as well as refrigerated corpses. They replicated potential time delays that could occur in the field by waiting for approximately 12 hours between the glue fuming (which could be done at the crime scene) and the application of fingerprint powders (perhaps conducted later at the morgue). The results showed that by following proper procedures, investigators could develop identifiable latent prints even under harsh conditions.


This research indicates that homicide victims should be examined for latent prints whenever investigators believe that the perpetrator touched the victim. If possible, bodies should be examined at the crime scene immediately after the coroner or medical examiner has completed an initial examination and granted permission. At a minimum, the body should be glue fumed at the scene to preserve the prints and help prevent contamination or obliteration of prints when the body is moved.

Ideally, bodies should not be refrigerated prior to examination for latent prints. The condensation that builds up on refrigerated bodies can have adverse effects by washing away the prints, reacting with the glue to distort the prints, or causing the powder to cake, thus losing the prints. Bodies that have been refrigerated should not be processed until the moisture evaporates, roughly several minutes, depending on ambient temperature. A control area of skin least likely to have prints can be tested to ensure that the moisture has dissipated.

Skin that is warm or near normal body temperature should be glue fumed for only 5 to 10 seconds. Colder skin should be glue fumed for a maximum of 15 seconds. Regular magnetic powders can then be applied. Any identifiable latent prints should be photographed first and then lifted using transparent lifting tape.


For many years, investigators and forensic scientists have tried to retrieve latent prints from dead bodies, but often the key evidence has been just out of reach. Frustrated, investigators often gave up after several failed attempts. This research proves that with practice, it can be done by those who are willing to try. As it becomes routine for law enforcement to obtain latent prints from skin, murderers who reach out to harm their victims will just be putting themselves within easy reach of the long arm of the law.


These are commonly used methods for developing latent fingerprints on a variety of surfaces. For more information, see Chemical Formulas and Processing Guide for Developing Latent Prints (Washington, DC: Latent Fingerprint Section, Laboratory Division, FBI, 1994).

Case Study: Conviction Through Enhanced Fingerprint Identification
12 years ago
This article originally appeared in the FBI Law Enforcement Bulletin, December 1992.

In March 1990, an unknown assailant sexually molested and fatally stabbed a young woman. At the crime scene, an investigator discovered few leads. The only evidence was a pillowcase, found adjacent to the victim's body, that exhibited several bloodstains. One stain showed some faint fingerprint ridge detail, barely visible even to the trained eye.

Preliminary Investigation

An investigator took the pillowcase to the department's forensic unit for bloodstain pattern analysis. Technicians photographed and studied the stains,slowly extracting information. They discovered two things. First, they confirmed that several stains were consistent with blood transfer from a knife blade, although no knife was found at the crime scene. Second, and more importantly, analysts determined that the fingerprint presented enough ridge detail to conduct a more extensive investigation.

Analysts then sent the evidence to another forensic study center where scientists treated the fingerprint with DFO, a relatively new chemical (similar to Ninhydrin) that becomes fluorescent when exposed to a light source. Once processed, the DFO provided an improved ridge detail photo. However, the ridge detail still remained blurred, displaying poor general continuity and visible fabric weave in the background. All traditional photographic techniques failed to erase the distortion. Analysts subsequently concluded that the latent was unidentifiable.

Image Enhancement

A short time later, investigators assigned to the case witnessed a demonstration of fingerprint image enhancement at a forensic conference. Faced with a dead-end murder investigation, they decided to try the technique on the unidentifiable pillowcase fingerprint from the crime scene. Investigators took the best DFO photograph and shipped it to a facility with the capability to perform image enhancement. Throughout the enhancement process,the accuracy of the print was documented through photographic records of each stage. Within 4 hours, the enhancement yielded an identifiable print.


In the interim, the lead case investigator developed several likely suspects. The primary suspect (the victim's next door neighbor) surfaced early in the investigation. However, the prints on record from a previous arrest did not contain sufficient ridge detail for comparison.

The investigator then concentrated on the serology report, which noted that examiners recovered seminal fluid from the victim during the postmortem examination. This preliminary serological report proved the seminal fluid matched that of the prime suspect, placing him in less than 5% of the general population. Encouraged by this breakthrough, examiners initiated the lengthy process of DNA analysis.

Using the serology report as probable cause for arrest, the investigators arrested the suspect and obtained a set of inked prints. After weeks of evaluation, comparison, and verification, the examiners achieved a positive identification comparison of the bloody pillow print with the left thumb of the suspect. Less than a week later, investigators received the DNA results,which further incriminated the suspect by matching his DNA code with that found in the stain on the pillowcase. This, in effect, placed the suspect as only 1 in 30 million people in the population with this particular DNA code.

Court Proceedings

During the suppression hearing, defense attorneys launched an attack on what they believed to be the most potentially vulnerable piece of evidence, the scientific acceptance of fingerprint image processing. To counter, an analyst took the court step by step through the entire procedure using a full complement of image enhancement equipment. An expert in the field of image processing then offered supporting testimony to the court.

Ultimately, the court ruled the enhanced print admissible, stating that the process did not alter the actual pattern of the print; it only made it more visible. The evidence passed the test, resulting in the first documented case where image enhancement technology withstood the challenges of a Frye hearing.1

Trial Results

One last piece of evidence emerged during final trial preparation. Maintenance men working in the defendant's vacant apartment discovered a military survival knife hidden in a pipe chase. Serological examination revealed traces of human blood, but no typing was possible. However, the shape and size of the sawtooth blade matched several of the blood stains on the pillowcase. Police personnel prepared a large transparent overlay for courtroom display to illustrate how the knife and the stain conformed to a single image.

12 years ago

Faced with overwhelming physical evidence, such as the image enhanced fingerprint match, the DNA test results, the match between the body fluid found on the victim's body and that of the suspect, and the knife found in the suspect'sapartment, defense attorneys entered four guilty pleas, one of which was for capital murder. On June 18, 1991, the court sentenced the accused to four life sentences for murder and related offenses.2


Five years ago, a suspect committing these types of crimes would most likely go free, due to a lack of substantial forensic evidence. However, through persistence and by applying such modern technologies as finger-print image enhancement, today's police investigators can use evidence invisible to their predecessors.

  1. Frye v. United States, 293F. 1013,1014 (D.C. Cir. 1923).
  2. Commonwealth of Virginia v. Knight, CR-90-1353-02-F.

Information for this case study was submitted by Norman Tiller, a latent print examiner, and Thomas Tiller, a crime scene investigator, both with the Henrico County Division of Police, Richmond, Virginia.

12 years ago
     Please stay tuned for our next series of articles, titled:Crime Scene Investigation
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