A forensic specialist believes one of the world's most high-profile unsolved abduction cases could be solved using the same DNA technology used to identify the elusive Golden State Killer.
Three years after "supermum" Sherri Papini was kidnapped while jogging near her home in Redding, Northern California, local authorities are no closer to an arrest.
But now a US forensic scientist says familial analysis of DNA traces from an unidentified male found on Ms Papini's clothing lead to a breakthrough, news.com.au reports.
US police used genealogy company GEDmatch to search uploaded genetic profiles that lead to the identification and arrest of one of the country's most prolific serial killers, Joseph DeAngelo in 2018.
The technology used to catch the killer and rapist has been described as like "a molecular eyewitness" enabling law enforcement to solve violent crimes "efficiently and with certainty".
Known variously as the Golden State Killer, East Area Rapist, the Visalia Ransacker and Original Night Stalker, DeAngelo terrorised California for decades, committing at least 13 murders, 50 rapes and 100 burglaries between 1974 and 1986.
The 72-year-old war veteran and former police officer was caught after authorities used DNA data sequences gathered from old crime scenes, and sifted through raw genetic profiles uploaded to GEDmatch until they found one, which shared enough markers to the perpetrator's blood relative.
The process is known as familial DNA profiling and can lead authorities to a perpetrator via the DNA of a relative as far down the family tree as a third cousin.
Ms Papini made global headlines when she disappeared on November 2, 2016 — only to resurface three weeks later in bizarre circumstances on Thanksgiving Day.
Grainy CCTV footage showed the then 34-year-old running near a ramp after her captors dumped her on the roadside near Interstate 5 in Yolo County at 4.30am some 240km from where she vanished.
When found, Ms Papini was still wearing restraints and suffering significant injuries including a broken nose and bruising to her body. Her long blonde hair had been chopped and she had lost a significant amount of weight.
In a sinister twist, she had been branded on one shoulder with a cryptic symbol, leading to speculation the youthful looking mother-of-two had been mistaken for a young girl by sex traffickers.
Shasta County detectives have never revealed an image of the symbol or described it but their fellow investigators in the FBI later released a sketch of two female suspects of Hispanic appearance based on the few details Ms Papini was able to provide.
They have never been identified but the victim claimed the pair was armed with a handgun and transported her to the spot where she was released in what appeared to be a dark-coloured SUV.
Detectives said Ms Papini's ability to describe her captors and surroundings was hampered because her head had been covered during most of her ordeal.
In a baffling development, forensic specialists found DNA traces from an unidentified male on her clothing and female DNA on her body.
The male DNA did not belong to her husband and neither sample matched profiles of any individuals on the FBI's Combined DNA index System (CODIS).
"Whereas CODIS needs past DNA from a perpetrator to make a match, consumer websites can crack a case as long as someone in the perp's family (third cousin or closer) has tried the tech," Redding Record Searchlight reporter Matt Brannon explained.
University of Illinois-Chicago forensic scientist Ashley Hall told the newspaper that if such technology could unmask a killer as elusive as DeAngelo, it could certainly lead to a breakthrough in the Papini case.
"Our technologies have greatly improved, and we now have the ability to generate a massive amount of sequence data," Prof Hall said.
This week, GEDmatch announced it had joined forced with forensic genomics giant Verogen Inc, in a move it claims will allow its DNA database to expand exponentially while protecting customers' privacy.
"The website gives users a choice to opt-in to allow law enforcement to search uploaded files as a tool to solve violent crimes," Verogen CEO Brett Williams said in a December 9 statement.
"Among the successes of this technology is work by public safety officials who used GEDMatch to apprehend accused Golden State Killer Joseph DeAngelo … As many as 70 violent crimes have been solved as a result of genealogy searches.
"Never before have we as a society had the opportunity to serve as a molecular eyewitness, enabling law enforcement to solve violent crimes efficiently and with certainty."
Shasta County Sheriff Tom Bosenko, who led the Papini investigation in conjunction with the FBI and fronted many fiery press conferences as the world's media grappled with the bizarre details of the abduction, recently retired.
But his successor, Captain Pat Kropholler, said the county not given up on solving the case.
"When you say something's cold, (it means) we just don't have an active lead to work on at the moment," Capt Kropholler told Searchlight.
"But it doesn't mean the case is closed."