PIERRE, S.D (KELO) — It was August of 1976, when a man’s decomposing body was found in the Missouri River near Pierre.

Despite investigators’ best efforts, the man discovered in the water couldn’t be named.

He was buried at Pierre’s Riverside Cemetery as an unknown man.

The case always bothered Cheryl Stone.

“I kept thinking there’s got to be someone looking for this gentleman,” Stone said.

Over the years, her mother, Gertrude, placed flowers on the unknown man’s grave.

Cheryl later took over tending to the grave.

In 2020 than Pierre Police Detective Trevor Swanson took on the cold case.

“Anytime that you have an individual in your community that has no identification, that has no name, he’s been put to rest under unknown circumstances, I think that we as law enforcement have a duty to try to answer some of those questions,” Swanson said.

In 2021, the body was exhumed with a permit, and samples were collected.

In 2022, Swanson remained on the case as a DCI special agent.

The DNA profile was compared to results found in genetic genealogy databases.

It resulted in a potential match for 39-year-old Stephen Earl Boice.

His last known address was Seattle, Washington.

“Mr. Boice was never reported as missing, in part I assume to his somewhat transient lifestyle. When no one heard from him they just assumed he was off living his life somewhere else,” Swanson said.

The South Dakota Forensic Lab compared the partial fingerprints collected in 1976 with a fingerprint card collected from Boice in the 1960s.

The prints matched.

“It really is an example of where excellent police work combined with modern technology we’re able to do miracles,” South Dakota Attorney General Marty Jackley said.

Boice now has a headstone at Riverside Cemetery with his full name.

Putting an end to the mystery is bittersweet.

“It feels good to know we were able to identify somebody who was previously known as “unknown man” and to put a name to this, to give him his name back, but at the same time, what is the elephant in the room is that there was a tragedy that led to this investigation,” Swanson said.

“You can think that maybe this isn’t important, but in fact, it is. It’s a person, and he was important,” Stone said.

That’s why Cheryl will continue caring for his grave.

Investigators say there’s no evidence of foul play in Boice’s death.

They’ve contacted Boice’s closest living relatives.

They requested he remain at Riverside Cemetery.