TAMPA (FOX 13) - They stumbled onto it by accident in the backyard of a North Tampa house. It was a gruesome discovery.
"He was floating in the pool," Tampa Police Homicide Sergeant Greg Van Heyst said.
It was May of 1989, and the man was face-down in the shallow end behind the vacant house.
Investigators determined the death was an accidental drowning, but they couldn't figure out who the man was.
"They never got the man identified, there were never any reports of a missing person that matched this male,” said Van Heyst.
The man was buried in a John Doe grave, and over the last 29 years, the case went cold.
In 2017, the unidentified man's body was exhumed from the grave. One of 110 unsolved cases across the country getting a second review through a cold case initiative by the University of South Florida's Institute of Forensic Anthropology and Applied Science.
Dr. Erin Kimmerle and her team essentially re-analyze unsolved deaths to hopefully unmask the dead.
"We just try to throw everything modern science has at these cases, a lot of them have been buried in John Doe graves for decades, and they don't have facial reconstructions or any updated information," Kimmerle said.
The skeletal remains are meticulously analyzed for clues. Chemical isotope and DNA testing reveal vital details.
Including new information about the mystery murder victim from 1989.
"We think he was probably born in the Southeast, but North of here, North of Florida,” said Kimmerle. “Maybe Tennessee, the Carolinas type of area, and then ended up here closer to the time when he died."
Using all of those details, Kimmerle was able to digitally re-create what John Doe likely looked like. A man between 25 and 35-years-old, who investigators now know was murdered.
"Through that examination, they were able to determine that the person in-fact died from homicidal violence," Van Heyst said.
Police hope the man's picture can help crack the cold case, and they can finally figure out his name as well as who killed him.
"Our hope would be that maybe some of these details will refresh somebody's memory, they think about someone they know, they love, that went missing they never heard from," said Van Heyst.
Officials say the key to closing many of these cases are for people to make sure their loved ones are reported missing, no matter how long ago they disappeared.