When he and his wife, Sharron, both 56, strolled into the Third Street Waterfall Park for a steel drum concert that evening, they held hands, observers say.

Nobody who saw them would have guessed that in a few hours, just as the sun would rise over Bay City, darkness and violence would consume the seemingly happy couple.

According to Bay City Police, who wrapped up their investigation on Tuesday, David Hetzel committed a series of crimes Saturday morning that left his wife and himself dead and their home at 406 N. Farragut St. destroyed by fire.According to investigators, this is how the tragedy unfolded in the early morning hours on Saturday:

David Hetzel armed himself with two chef's knives and what police believe was a golf club and attacked Sharron as she lay in bed, striking her in the head and stabbing her repeatedly.

He then dashed through the Victorian home, from which they were being evicted, starting fires in several locations and setting a large blaze in the basement.

He gulped smoke as he climbed the stairs to the second-story bedroom a final time, slipped into bed beside his dead or dying wife, and picked up one of the knives. With one swift motion, he inflicted a single, fatal wound to his torso.

Such are the conclusions of investigators from the Bay City Police Department.Detectives - along with arson specialists from the Michigan State Police and the Bay County Medical Examiner - have been piecing the evidence together since Saturday morning.

"For whatever reason, he killed his wife and committed suicide," said Bay City Police Chief Michael J. Cecchini. "It's a tragedy."

The "how" seems to have been explained, but the "why" remains a mystery, the chief said.Bay City firefighters and police officers arrived at the house around 6:45 a.m. and found the doors locked, according to Detective Sgt. Joseph A. Lanava.

Officers forced a rear door open as firefighters busted in the front door. Fire personnel discovered the couple in an upstairs bedroom, and removed both bodies through a bedroom window.

Both of the Hetzels were pronounced dead at the scene, and autopsy results later showed that Sharron died of "multiple stab wounds and blunt force trauma to the back of her head," and that David died from a "single stab wound on his torso."

David Hetzel was a chef who had worked for the former Holiday Inn hotel in Bay City before opening The Really Darn Good Food Company in downtown Bay City in 2006.

The restaurant closed earlier this year and David Hetzel was attempting to launch a catering business. Sharron Hetzel was executive director of Studio 23/The Arts Center until resigning in June, and previously worked as an administrator for the Girl Scouts of Mitten Bay. The couple is survived by two adult daughters and a grandson.

Cecchini said he has not seen the letter that David Hetzel wrote to his daughters, and is unsure if it provides insight into his state of mind."He does make some apologies," Cecchini said.

Joy Butler, director of the Bay Arts Council, said that Sharron Hetzel was an "effervescent" woman who loved art, children and laughter."Sharron was just fun," Butler said. "She had a great sense of humor and a real flair, both in her personal taste and in what she looked for in art."

Butler said she's spoken to the Hetzels' twin daughters, Kristin and Bre, who are in their late 20s, and they are "doing as well as could be expected.""It's not easy," Butler said. "We had some tears today."Kristin resides in Bay City and has a young son, Austin. Bre is on Mackinac Island for the summer, where she is working as a chef, Butler said.

The Hetzels had lost their home to foreclosure and also had filed for bankruptcy protection but did not follow through with the Chapter 13 proceedings.

Butler said the Hetzels seemed to care deeply for one another, and that she witnessed them holding hands at the park Friday evening.

"I really hope that people support the girls and I hope they remember the good things," Butler said, "because there were a lot of good things."

Funeral services are scheduled for 11 a.m. Saturday at Westminster Presbyterian Church, 103 E. Midland St. Visitation will be from 1-9 p.m. Friday at the Squires Funeral Home, 211 N. Henry St.

Sharon Hetzel is the third woman slain on the East Side of Bay City since June. The body of Pamela Wilson, 37, was found in an upstairs apartment at 310 Garfield Ave. on June 16. Christopher K. Wilson, 25, has been charged with an open count of murder but has been deemed incompetent to stand trial and is undergoing psychiatric treatment.

Holly Falasz, 29, was found dead in her home at 318 Jennison St. on July 25. Her children, ages 5 months, 4 and 8 years old, were home but unharmed in the attack.

Police Chief Cecchini said that case is a homicide and that it appears the killer remains at large, though he said he does not believe the killer poses a threat to the general public.

Times Writer Patti Brandt contributed to this report