Investigators in Washington State have unveiled a suspect image created from DNA in the 1987 murders of a young Victoria-area couple.

The Snohomish County Sheriff's office held a news conference in Everett, Wash. Wednesday to provide an update on the more than 30-year-old cold case.

Tanya Van Cuylenborg, 18, and Jay Cook, 20, set out on a trip to Seattle on Nov. 18, 1987, and were last seen by their families as they boarded a ferry in Victoria to Port Angeles.

Six days later, Cuylenborg's body was found in northern Snohomish County in Washington State. Her hands had been bound by plastic zip ties and investigators determined she had been sexually assaulted and then shot.

Cook's body was found beaten and strangled a few days later on Nov. 26.

Their killer was never found, and no suspects were ever arrested in the case.

Decades later, and investigators have now put together what they believe is an accurate prediction of the murderer's appearance, thanks to technology called snapshot DNA phenotyping that can determine a person's eye, skin and hair colour, facial features and ancestry.

The snapshot shows three images of what the suspect may have looked like at 25, 45 and 65 years old. He's depicted as a white male of European descent with hazel or green eyes, light hair, vary fair skin, possible freckles and possible male pattern baldness. Investigators say the DNA profile doesn't account for weight, facial hair or other features like scars.

Police and family of the vicitms hope it will lead to a significant break in the three-decade-old cold case.

"When your brother or sister, daughter or loved one walks out the door, you have no way to know it's the last time you'll ever see them," said Cook's sister Laura Baanstra. "This was a calculated crime. This wasn't some random one time violent act. This person worked their way up to this. Someone out there knows something. This person could've talked or braggedabout these events in November 1987."

The family has put up a $50,000 reward for any information that leads to the arrest or identification of the person who killed Cook and Van Cuylenborg.

"We are looking for anyone who knows something related to this case, or can identify a person of interest from the Parabon DNA predictions and images,” said Investigations Captain Jeff Miller. “Maybe you were too afraid to come forward at the time, or thought someone else would. Now is the time to share what you may have seen or heard.”

Investigators previously pursued what was thought to be a break in the case in 2010 after dozens of disturbing letters were sent to the families of the slain victims as well as police.

A homeless man found in Vancouver admitted to writing the letters, but through DNA analysis, he was cleared of the murders.

The case was so high-profile that it became the subject of an episode of Unsolved Mysteries.

Anyone with information is asked to call the Snohomish County Sheriff's Office tip line at 425-388-3845.