Familial DNA was used to solve a case that had gone cold for over 40 years in Sonoma County, the case of the 1982 murder of 13-year-old Sarah Geer in Cloverdale.

Sarah Ann Geer was killed May 23, 1982. She was reportedly walking home from a friend's house in quiet downtown Cloverdale when she was forcibly dragged down an alley to a secluded location where she was, according to the Sonoma County District Attorney's Office, "brutally raped" and "strangled ... to death using her own shorts as a ligature."

The killer left behind plenty of DNA evidence, however that DNA was not tested until many years later, and the case went entirely cold. It was over 20 years go, in 2003, that a DNA profile was developed from semen found on Geer's clothing, however it was not a match to anyone in existing law enforcement databases.

That all changed, as KRON4 reports, after a private investigator was hired by the Cloverdale Police Department in 2021, and with the help of the FBI, they employed the same technique used to find the Golden State Killer, the use of genetic genealogy.

Prosecutors say that Geer's killer was determined to be one of four brothers, and investigators homed in on 66-year-old James Unick, a resident of Glenn County, California, who would have been 22 at the time of the murder, and who lived in Cloverdale at the time. After collecting a cigarette smoked by Unick and testing it for DNA, Unick came up as a complete match for the DNA found on Geer's clothing, and he was arrested in July 2024.

Earlier this month, while on trial for the murder, Unick took the stand and admitted to having had sex with the 13-year-old, but said he did not kill her, as the Press Democrat reported. Unick told the jury that the girl had propositioned him for sex, and because he knew it was wrong, due to her age, he had kept it secret.

"I did not strangle anybody," Unick said in court.

Cheryl Evans, Geer's best friend at the time, testified that Geer had stopped by her house on her way home the night of the murder, around 11 pm on a Sunday, and nothing had seemed out of the ordinary. Geer was last seen at an arcade where Unick said he'd been playing a game, and her body was later discovered by two children behind an apartment building.

On Friday, a Sonoma County jury found Unick guilty of the muder, and he is now set for sentencing on April 23.

"This is the coldest case ever presented to a Sonoma County jury,” said District Attorney Carla Rodriguez in a statement. “While 44 years is too long to wait, justice has finally been served, both to Sarah’s loved ones as well as her community."

Following Unick's arrest, the mayor of Cloverdale at the time, Todd Lands, said, "Today, we stand united in solidarity with the Geer family as we witness the culmination of years of hard work and perseverance by our law enforcement officials."

And Cloverdale Police Chief Chris Parker said, "Today represents a bittersweet victory for justice. While nothing can undo the pain inflicted upon the Geer family and our community, we can finally offer some solace in knowing that the perpetrator will be held accountable."