July 25, 2019, 5:09 PM ET

Cold Cases

In 1987, William Talbott II killed Jay Cook, 20, and Tanya Van Cuylenborg, 18, while they were vacationing in Washington State.

By The Associated Press

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A man convicted of killing a young Canadian couple more than three decades ago after a trial that hinged on DNA evidence and newly-emerged genealogical technology was sentenced in Washington state Wednesday to life in prison.

William Talbott II received two consecutive life terms with no parole, The Daily Herald reported.

Tanya Van Cuylenborg, 18, and her 20-year-old boyfriend, Jay Cook, disappeared in November 1987 after leaving their home near Victoria, British Columbia, for what was supposed to be an overnight trip to Seattle. Their bodies were found in separate locations in northwestern Washington state about a week later.

Investigators preserved DNA evidence but they didn’t know whose it was until last year. Authorities used genetic genealogy to identify the suspect as Talbott, a construction worker and truck driver who was 24 at the time of the killings and lived near where Cook’s body was discovered.

Talbott, now 56, did not testify during the trial and jurors rejected a suggestion from his lawyers that he had sex with Van Cuylenborg but did not kill her or her boyfriend. It’s still unknown how Talbott encountered the pair and what exactly happened before they were killed.

William Talbott II at the Snohomish County Courthouse on Friday, June 14, 2019. Photo: Andy Bronson/The Herald/ AP

Jay Cook’s mother believes her son pulled over to help a stranger on a cold night. “Jay would’ve picked anyone up, on a night like that,” Lee Cook said in court Wednesday.

When the couple didn’t return from their trip, their families began a search that included renting a plane to find the copper-colored Ford van they had been driving.

About a week later, 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 two days later in brush near a bridge over the Snoqualmie River — about 60 miles (95 kilometers) from where his girlfriend was discovered. He had been beaten with rocks and strangled with twine and two red dog collars, authorities said.

Prosecutors said once Talbott became a suspect, investigators picked up his discarded coffee cup and tested the DNA from it, confirming it matched evidence from the crime. He has maintained his innocence since his arrest.

“The level of violence in this is something that I cannot comprehend,” Talbott told the judge Wednesday. ” . I’ve gone all my life as a very passive person.”

A lab report unsealed after the jury’s conviction showed investigators found additional DNA from Talbott on zip ties discovered at the crime scene, The Herald reported earlier this week.

Talbott is one of dozens of suspects authorities have arrested in old cases over the past year through the genetic genealogy, 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 in that case.

In Talbott’s case, a genetic genealogist used a DNA profile entered into a database to identify distant cousins of the suspect, build a family tree linking those cousins and figured out that the sample must have come from a male child of William and Patricia Talbott.

The couple had only one son: Talbott.

Van Cuylenborg’s older brother John said he views the technology as not only a great way to solve cases, but as a strong deterrent. “Society really owes an obligation to these kids, and to itself, to make use of this tool,” he said. “We’d be very much the worse off if we don’t take the opportunity to use this technology to make our society a safer place for everyone.”