Police are hoping revolutionary DNA technology will lead them to a suspect in the cold case of a young B.C. couple killed 30 years ago in Washington state.

Tanya van Cuylenborg, 18, and Jay Cook, 20, of Saanich, were last seen on Nov. 18, 1987.

The high school sweethearts took a ferry from Victoria to Port Angeles, Wash., on what was supposed to be an overnight trip to Seattle. Both of their bodies were found within days of their disappearance and police have been baffled by the case ever since.

Images of a suspect in the double homicide have been created using DNA collected back in 1987. They show a Caucasian, green or hazel-eyed, blond-haired man at ages 25, 45 and 65.

Laura Baanstra, sister of Jay Cook, speaks to reporters at a news conference Wednesday at the Snohomish County Sheriff's Office. (Karin Larsen/CBC)

According to the information gleaned from DNA, the man may also have freckles and be thinner or heavier than the images indicate. Detectives believe whoever the killer is likely bears a strong resemblance to the images.

The sister of Jay Cook says she hopes the photos will spark new tips in the case.

"If these pictures from this new, amazing technology triggers a memory ... please come forward for the sake of my brother Jay and Tanya. Call it in," said Laura Baanstra.

New DNA technique

The technique used is called Snapshot DNA phenotyping and is a relatively new procedure that involves using DNA to predict the physical appearance and ancestry of a suspect or unknown person.

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

"We've used it in over 150 cases and with 100 different agencies both in the U.S. and internationally," said Ellen McRae Greytak of Parabon Technologies, the company behind Snapshot DNA.

"We've helped solve quite a number of cases, [some] as old as 25 years."

Baanstra said she had yet to work up the courage to look at the images.

"That may be the face of the person who killed my brother," she said, choking back tears. "That's tough."

Cold case detective Jim Scharf, who works in Snohomish County, Wash., said if nothing else, the photos help rule out anyone with dark skin or dark hair being a suspect.

"We hope that this new technology will help us positively identify a suspect and finally provide answers for their families," said Scharf. "We believe that someone knows who our person of interest is."

Jay Cook and Tanya van Cuylenborg were killed in Washington state 30 years ago. (Crime Stoppers)

Cook, 20, and van Cuylenborg, 18, were reported missing Nov. 20, 1987, after taking the 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.

"The person who did this came prepared to do a brutal crime," said Scharf, who has worked on the case for 13 years.

Despite numerous public appeals over the years and and a number of crime shows profiling the homicides, detectives had exhausted all leads.

Jay Cook's body was found under this bridge in Monroe, Wash. He had been beaten and strangled to death. (CBC archives)

"Their killer has never been identified, and the DNA has never come back with a positive hit," said Snohomish County Sherrif Ty Trenary. "With this, we may be one step closer to identifying the killer."

"It gives us hope," agreed Sgt. Jennifer Sheahan-Lee of the Skagit Country Sheriff's Office.

Cook and van Cuylenborg's families have put forward a reward of $50,000 that will stand until the end of this year in exchange for information leading to the identification of the suspect.

"This was a cold and calculated crime. This person could have talked or bragged about this event," Baanstra said. "Even just the smallest piece of information could help."

Anyone with information can call 425-388-3845.