Bill Talbott, a 56-year-old Washington state man, has been found guilty of murdering Tanya van Cuylenborg and Jay Cook.

A jury in Everett, Washington, returned a verdict after two days deliberating over a cold case murder from 1987.

Tanya, 18, and Jay, 20, were Canadians on an overnight trip to Seattle to pick up furnace parts for Jay’s dad’s company.

[Read our in-depth story on this case.]

They were found brutally murdered, their bodies dumped in Snohomish and Skagit counties.

This was not just a sordid murder case. This was the first time a suspect found using genetic genealogy has been put on trial.

Genetic genealogy pointed investigators to the Golden State Killer in California – charged with 13 murders and countless rapes — which got law enforcement in Washington state considering what that could mean for cold cases here.

Genetic genealogy involves forensic researchers uploading a DNA profile to a public database of DNA profiles, finding a relative, and then perusing that relative’s family tree to identify a suspect.

After the Golden State Killer was nabbed last year, Washington state law officials saw an opportunity. They uploaded the DNA profile of the mysterious man, dubbed “Individual A,” into a genetic database.

Two second cousins popped up, a genetic genealogist perused his family tree, and within days, Bill Talbott of Monroe, Washington, became suspect number 1.

A DNA test confirmed that Talbott’s semen was found in Tanya and at the scene of the crime.

Talbott could appeal this conviction, but genetic genealogy would not be allowed to be part of this appeal, as the defense did not challenge the veracity of the method used to identify Talbott.

Rather, the defense argued that the semen proves only that Talbott and Tanya had sex. The defense also noted that Tanya’s fluid was in the sample – evidence of arousal.

The prosecution shot back: That was not evidence that she was turned on.

The defense also said that Talbott had rented a room from a cop in the 1990s – no murderer would do that, she said. He had also passed a federal background check. The prosecution side-eyed both of those statements in the rebuttal, drawing chuckles from the gallery.

This story was originally published on June 28, 2019.