A 55-year-old Seattle-area man has been arrested in the cold case double homicide of a young B.C. couple who were killed in Washington state more than 30 years ago.

William Earl Talbott II was taken into custody after a DNA test came back as a positive match to DNA collected from the crime scene more than three decades ago. His bail has been set at $2 million US.

Tanya van Cuylenborg, 18, and Jay Cook, 20, both of Saanich, B.C., were last seen alive on Nov. 18, 1987. Their bodies were found within days of their disappearance, and police had been baffled by the case ever since.

'Relief, joy, sorrow'

"For my family it is the end of the hurt that comes from not knowing who killed Jay and Tanya," said Laura Baanstra, Jay Cook's sister. "This arrest brings relief, joy, and great sorrow."

Talbott is expected to be charged later today with kidnapping, rape, double murder and robbery, according to Snohomish County Sheriff Ty Trenary.

Investigators said Talbott was 24 years old at the time of the killings, living in Woodinville, Wash.

He has worked as truck driver over the last 20 years and was arrested leaving work yesterday. He had no criminal record save for a charge of indecent exposure and was never the subject of a tip or on any law enforcement list.

DNA breakthrough

Talbott was identified through the same DNA genealogy analysis used to capture the Golden State killer last month.

Experts from Parabon NanoLabs in Virginia were able to identify Talbott's great grandparents and family tree using public genealogy databases. They then worked forward to identify Talbott himself.

Police subsequently obtained a DNA sample from a cup Talbott had used to make the positive identification.

"Without [genetic genealogy] we wouldn't be here today," said Skagit County Sheriff Will Reichardt.

Genealogy experts were able to identify Talbott's family tree and work backward to identify him as a suspect. (Snohomish County Sheriff's Office)

In November 1987, Cook and van Cuylenborg took a ferry from Victoria to Port Angeles, Wash., on what was supposed to be an overnight trip to Seattle.

A week after the couple vanished, van Cuylenborg's body was discovered in a ditch 20 kilometres south of Bellingham, Wash. Police said she had been raped and shot in the head.

Cook's body was discovered under a bridge in Monroe, Wash., a couple of days later. He had been beaten and strangled.

Jay Cook's body was found wrapped in a blue blanket under this bridge in Monroe, Wash., 11 kilometres from Talbott's parents' home. He had been beaten and strangled. (CBC archives)

Despite numerous public appeals and crime shows profiling the homicides over the years, detectives were stumped.

Last month, a new technique using the suspect DNA collected from van Cuylenborg's crime scene was used to create sketches of what the killer may have looked like.

DNA analysis provided the information to create these images of a potential suspect at ages 25 and 45. (Snohomish County Sheriff's Office)

Detectives said the sketches were helpful, but Talbott's appearance did not entirely resemble them because he is much heavier in real life.

Members of the van Cuylenborg and Cook family spoke at the news conference, thanking detectives and the experts behind the genealogy mapping.

"Science and good police work is making it harder for these criminals to hide in the shadows," said Baanstra.

Detectives also want to hear from anyone who saw Talbott associated with the Cook family van in November 1987 or with a 35mm Minolta camera that Tanya had in her possession when she was murdered. <a href="https://t.co/TTU2X22zMi">pic.twitter.com/TTU2X22zMi</a> —@SnoCoSheriff

Talbott is not currently being investigated for any other crimes, although investigators are still asking for the public's assistance, specifically from anyone who:

Knew Talbott or knew of his activities in 1987 or 1988.

Saw Talbott associated with the Cook family van in November 1987.

Saw Talbott with a 35-mm Minolta camera that Tanya had in her possession when she was killed. (The camera's lens was recovered and traced to a pawn shop in Portland, Ore., in 1990, but the camera body is still missing.)

Has information about Talbott having access to a light blue blanket which was found with Cook's body.

Anyone with information is asked to call 425-388-3845.