A Florida police department says it solved a 35-year-old homicide by using DNA to find a relative of the alleged killer and then created a family tree to track him down. Pensacola detectives arrested 57-year-old Daniel Wells on Wednesday and charged him with the slaying of Tonya McKinley, 23, whose body was found before dawn on New Year's Day 1985.

She had been strangled and sexually assaulted, according to the Pensacola News Journal. She left behind an 18-month-old son.

"This was a case that spanned three generations of detectives," said Pensacola police Capt. Chuck Mallett, who led the investigation. "I know it took a long time, but it was one of those cases we never gave up on."

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McKinley had last been seen at a Pensacola bar at about 1:30 a.m. New Year's Day. Her partially nude body was found four hours later in an empty lot by a family taking their dog to the emergency vet. No suspects had been publicly identified since and police found no DNA matches.

Tonya loved life. She made the most of every day. She was always looking for ways to make her friends laugh. She never... Posted by Pensacola Police Department on Thursday, March 19, 2020

"Despite having a good bit of physical evidence and dozens of interviews, over time, the trail went cold," police said in a Facebook statement. "It seems that every couple of years a new lead would pop up and we would drop everything to run it down. We did this time and time again. In the meantime, a baby boy grew up without a mother, parents buried their daughter without knowing justice, and a killer was walking around free. "

But over the last two years, police departments have begun running profiles of DNA left behind at old murders and sexual assaults against online databases where genealogy hobbyists and others post their DNA profiles in hopes of finding long-lost relatives. When detectives find DNA that suggests someone is related to the killer or rapist, they make a family tree of that person looking for male relatives who lived near where the attack took place.

If they find a possible hit, detectives surreptitiously follow the suspect until he discards a coffee cup, piece of gum or something else that would have his DNA. They recover and test the item, hoping for a match.

Police say that's what happened here - DNA recovered from a cigarette butt Wells discarded matched McKinley's killer. He is being held at the Escambia County Jail without bond, charged with murder and sexual battery. Court records do not list an attorney representing him. The News Journal said Wells had two arrests within three years of McKinley's death: one for battery and the other for soliciting a prostitute. He pleaded no contest to the battery charge.

McKinley's son, Timothy Davidson Jr., is now in his mid-30s. He told the News Journal he was happy to learn of the arrest.

"My mom, she never got to raise me, never got to be a part of my life," Davidson said. "(Wells) got to live his life the last 35 years. He got to have a family. He got to be around his children ... and all those years he was out there, knowing what he did. He was carrying it around with him and he was never going to tell anyone what he did. He wasn't going to ever just say what he did on his own.

"Nothing could ever make up for losing my mom, but at least now we know what happened to her."