The first person to ever be convicted as a result of genealogy research has been handed two life sentences for killing a young B.C. couple in 1987.

William Talbott II, 56, was sentenced on Wednesday at Snohomish County District Court in Everett, Wash. The sentences are to be served consecutively.

Jay Cook, 20, and Tanya Van Cuylenborg​​​​, 18, were travelling from Saanich, B.C., to Seattle for an overnight trip in November 1987 when they disappeared. Their bodies were found days later in rural areas in Washington.

It took 30 years and family tree research by genealogist Cece Moore to identify Talbott, whose DNA was found on Van Cuylenborg's body, and also on her pants and zip ties found in the couple's van.

Police in Washington state used information from public genealogy websites to pinpoint Talbott as a suspect, then arrested him after getting a DNA sample from a cup that fell from his vehicle.

Van Cuylenborg's body was found down an embankment in rural Skagit County, north of Seattle. She had been shot in the back of her head.

Cook's body was found two days later near a bridge over the Snoqualmie River in Monroe, Wash. He had been beaten with rocks and strangled.

Police in Washington state say they used information from public genealogy websites to pinpoint William Earl Talbott II as a suspect, then arrested him after getting a DNA sample from a cup that fell from his vehicle. (Charles Biles/Associated Press)

On Wednesday, Van Cuylenborg's brother John and Cook's parents Leona and Gordon, as well as his two sisters Lauralee and Kelly, were present in court for the sentencing.

The only person present from Talbott's family was one of his second cousins, Chelsea Rustad, whose DNA helped to identify him. She sat between John Van Cuylenborg and Jay's father Gordon during the sentencing.

Four men who appeared to be Talbott's friends were also present.

Rustad, who met the two victims families for the first time, said she was happy to be able to support them.

"It felt really good to be part of that and to be present with them and be able to introduce myself face-to-face and just to let them know that I support them in every capacity," said Rustad.

She said she did not feel conflicted about the fact that Talbott is her cousin and that her DNA helped to convict him.

"Absolutely not, in light of the horrific nature of the crime. And of course, he's guilty of the crime, there's absolutely no defence there that would make any sense."

The Fifth Estate reached out to several members of Talbott's family for comment — including his father and two surviving sisters — but they did not respond.

Talbott was arrested in May 2018 and convicted on June 28, 2019.

The Fifth Estate is producing a documentary about the murders of Jay Cook and Tanya Van Cuylenborg. It will be broadcast as part of our 45th season, which begins on Sept. 22.