A Washington state man was convicted Friday in the 1987 killings of a young Canadian couple, a trial that hinged on 32-year-old DNA evidence and newly emerged genealogical technology.
Jurors deliberated for more than two days before reaching their verdict against William Earl Talbott II, Seattle news station KOMO reported .
Talbott was arrested last year in the deaths of 18-year-old Tanya Van Cuylenborg and her boyfriend, 20-year-old Jay Cook.
Investigators used a method that identifies suspects by entering crime-scene DNA profiles into public databases that people have used for years to fill out their family trees.
He is one of dozens of suspects authorities have arrested in old cases over the past year through the genetic genealogy technique, including a California man charged in the Golden State Killer case.
The serial attacker killed 13 people and raped nearly 50 women during the 1970s and 1980s.
Once Talbott became a suspect in the Canadian couple's deaths, investigators tailed him, saw him discard a coffee cup and then tested the DNA from the cup, confirming it matched evidence from the crime, prosecutor Justin Harleman told jurors.
Van Cuylenborg and Cook disappeared in November 1987 during what was supposed to be an overnight trip from their hometown of Saanich, British Columbia, to Seattle to pick up furnace parts for Cook's father's business.
After a frantic week for their families, Van Cuylenborg's body was found down an embankment in a rural area north of Seattle. She had been shot in the back of the head.
Hunters found Cook dead two days later next to a bridge over the Snoqualmie River, about 60 miles (95 kilometers) from where his girlfriend was discovered. He had been strangled with twine and dog leashes.
Over the next three decades, detectives investigated hundreds of leads to no avail. But in 2017, Snohomish County sheriff's detective Jim Scharf learned about Parabon Labs in Reston, Virginia, which was using a new method to extract more information from DNA samples.
With a sample from Van Cuylenborg's pants discovered in the couple's van in Bellingham, Washington, after their deaths, Moore built a family tree and determined that the source must be a male child of William and Patricia Talbott.
William Talbott II, now 56, was their only son. He was 24 at the time of the killings and lived near where Cook's body was found.