The Washington state man convicted of murdering a Vancouver Island couple more than 30 years ago will spend the rest of his life in jail without the possibility of release.

William Earl Talbott II was convicted last month in the 1987 murders of 18-year-old Tanya Van Cuylenborg and 20-year-old Jay Cook, both of Saanich. On Wednesday he was handed two life sentences for the crimes.

Talbott is one of dozens of men authorities have arrested for unsolved crimes in the past year using new genealogy matching techniques. The practice involves identifying suspects by entering crime-scene DNA profiles into public databases that people have used for years to fill out their family trees.

Talbott, of SeaTac, Wash., spoke before his sentencing Wednesday, professing his innocence in the brutal murders of the young couple.

"I stand before you a man convicted of a crime that I did not commit," Talbott told the Washington state courtroom.

"The level of violence in this is something that I can't even comprehend. I've gone all my life as a very passive person – never raised my hand towards anybody."

Talbott went on to say, "I have never fired a handgun in my life."

Defence attorney Jon Scott described Talbott as an "honourable man" who " has lived his life just working hard."

The comments were preceded by victim impact statements, many of which described a Cook as a friendly, caring young man who "would give you the shirt off his back."

Prosecutors convinced a jury that on Nov. 18, 1987, Cuylenborg and Cook drove a van from Saanich to Seattle for an overnight trip.

When they didn't return, their families began a frantic search for them, including renting a plane to try to spot the copper-coloured Ford van they had been driving.

About a week later, Van Cuylenborg's body was found down an embankment in rural Skagit County, north of Seattle. She was naked from the waist down and had been shot in the back of the head.

Hunters found Cook dead two days later in brush near a bridge over the Snoqualmie River in Monroe, which is about 95 kilometres from where his girlfriend was discovered. He had been beaten with rocks and strangled with twine and two red dog collars, authorities said.

The couple's van was found in Bellingham, near a bus station. Van Cuylenborg's pants were in it; investigators found semen on the hem, and said it matched that on her body. Investigators determined that it belonged to Talbott.

Talbott wasn't arrested until last year and was convicted on June 28, 2019.