More than four decades after a teenager was murdered in California, DNA found on a discarded cigarette has helped authorities catch her killer.
Sarah Geer, 13, was last seen leaving her friend’s house in Cloverdale, California, on the evening of May 23, 1982.
The next morning, a firefighter walking home from work found her body, the Sonoma County District Attorney’s Office said in a news release. She had been dragged down an alley to a secluded area near an apartment building and behind a fence, where she was raped and strangled, according to authorities.
Her death was ruled a homicide, but due to the “limited forensic science of the day,” no suspect was identified and the case went cold for decades, prosecutors said.
Nearly 44 years after Sarah’s murder, a jury found James Unick, 64, guilty of killing her on February 13. It would have been the victim’s 57th birthday, the Sonoma County District Attorney’s Office told CNN.
Genetic genealogy, which combines DNA evidence and traditional genealogy, helped match Unick’s DNA from a cigarette butt to DNA found on Sarah’s clothing, according to prosecutors.
“This guilty verdict is a testament to everyone who never gave up searching for Sarah’s killer,” District Attorney Carla Rodriguez said in the release. “This is the coldest case ever presented to a Sonoma County jury. While 44 years is too long to wait, justice has finally been served, both to Sarah’s loved ones as well as her community.”
A break in the case first came in 2003, when investigators developed a DNA profile based on sperm collected from Sarah’s underwear, prosecutors said.
However, the profile did not match anyone whose DNA was available for comparison in law enforcement databases at the time, according to the release, and the investigation came to a halt again. Those databases include information of known criminal offenders.
In 2021, the Cloverdale Police Department reopened the investigation into Sarah’s death. The department said it had been in communication with a private investigation firm in late 2019 and had partnered with them in hopes the firm could revisit the case’s evidence “with the latest technological advancements in cold case work.”
The investigation also enlisted the FBI to help identify a potential match to the 2003 DNA profile.
“The FBI, with its access to familial genealogical databases, concluded that the source of the DNA evidence collected from Sarah belonged to one of four brothers, including James Unick,” prosecutors said.
Once investigators narrowed down the list of suspects to the four Unick brothers, the FBI “conducted surveillance of the defendant and collected a discarded cigarette that he had been smoking,” prosecutors said.
A DNA analysis of the cigarette confirmed James Unick’s DNA matched the 2003 profile, along with other DNA samples collected from Sarah’s clothing the day she was killed.
Investigators were able to crack the case thanks to the emerging field of genetic genealogy, which combines DNA analysis and family tree research.
Essentially, a DNA sample is compared to publicly accessible databases of millions of people who have contributed their genetic profile, and investigators can then piece together a family tree that leads to a suspect.
In 2018, genetic genealogy led to the arrest of the Golden State Killer, and it has recently helped solve several other cold cases, including a 1974 murder in Wisconsin and a 1988 murder in Washington. Investigators in Nancy Guthrie’s disappearance recently announced they would turn to genetic genealogy to analyze unknown DNA found in her house.
Police arrested Unick in July 2024 at his home in Willows, California.
“Today represents a bittersweet victory for justice,” Cloverdale Chief of Police Chris Parker said in a 2024 statement following Unick’s arrest. “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.”
At the time of his arrest, Unick maintained he did not know Sarah or remember the events of the night of her death. During the monthlong trial, his story changed.
Unick testified the teenager “propositioned him for sex while he had been playing a video game” at an arcade in Cloverdale, and claimed the two had engaged in consensual sex on a hillside near a local river, according to prosecutors.
Prosecutors also said Unick implied Sarah had been assaulted and killed by someone else later that night.
Jurors additionally heard from friends of Sarah who had spent time with her during her last weekend alive in 1982.
Following two hours of deliberations, the jury rejected Unick’s account of events and convicted him of murder, prosecutors said.
As a result of the guilty verdict and since the jury found “the defendant committed a special circumstance related to the sexual assault during the commission of the murder,” Unick will be sentenced to life in prison without the possibility of parole, according to prosecutors.
He is scheduled to be sentenced on April 23.
