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Leanne Tiernan case
13 years ago

Leanne Tiernan

Leanne Tiernan

The murder of 16-year-old Leanne Tiernan and the discovery of her body months after her disappearance, led to the involvement of the Forensic Science Service (FSS.) scientists from a range of different fields.

Their job was to help provide compelling evidence to aid the police in the hunt for the killer.

Discover how forensics was used to convict her murderer.

In August 2001, West Yorkshire Police launched a murder investigation following the discovery of Leanne's body, almost nine months after she went missing. Fingerprints, DNA and clothing all identified the body as that of the missing Leeds teenager, but they still needed to find the murderer.

FSS experts were drafted onto the murder investigation team and co-ordinated the complex and vital forensic input that eventually linked suspect John Taylor to the crime.

Leanne's body was discovered wrapped in a duvet cover and a number of green plastic refuse sacks. A black plastic bag held in place by a dog collar covered her head, a scarf and plastic cable ties had been tied around her neck and cable ties bound together her wrists.

From all of this evidence, the FSS scientists were optimistic they would obtain a DNA profile or fingerprint, but the condition of Leanne's body was such that the materials were contaminated and repeated tests failed. Analysis of fibres and twine, mitochondrial DNA testing and even work on dog DNA, were all carried out in the hope of finding a clue that would point to the schoolgirl's killer.

They then concentrated their efforts on building up a forensic picture of the offender by using some alternative forensic techniques. This work, combined with excellent work relating to the supplier of the dog collar and cable ties, ultimately led the police to Taylor.

The evidence

Scarf: scientists examined the knitted scarf found around Leanne's neck and discovered hairs caught in the knot. 'Conventional' DNA tests on the roots of these hairs failed, so mitochondrial DNA testing was carried out and an FSS scientist obtained a DNA profile from the minute amounts of DNA inside the hair shaft which matched Taylor.

Twine: FSS experts examined the twine and discovered that it had an unusual composition. Examination of twine found at Taylor's home found it to exactly match that used to tie up the green bin bags. It was traced to a manufacturer in Devon who sold it for rabbit netting, only a small 'one-off' batch was ever made.

Carpet fibres: red nylon carpet fibres were recovered from Leanne's jumper. When these were examined they were found to be very distinctive, due to the unusual way in which the fibre had been dyed. Examination of carpet fibres belonging to Taylor, which he had tried to burn, showed a match.

Dog hairs: animal hairs were found on Leanne's body and an FSS scientist took a sample of them to a Texan university that had developed DNA profiling for dogs, principally for pedigree research. A partial DNA profile of a dog was obtained. The results did not help the case, as the dog Taylor owned at the time of Leanne's abduction had died. However, this was the first time a dog's DNA profile was obtained in a British case.

The summing up

Taylor received two life sentences at Leeds Crown Court after admitting the kidnap and murder of Leanne.

BBC Crime gratefully acknowledges the help of the Forensic Science Service for providing this article.

13 years ago
     It is incredible how the FSS used these individual pieces of evidence to convict the killer.....One life sentence for the kidnapping and one for the murder, that is a good sentence....
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