'She's precious to me:' Snohomish cold case detective identifies Jane Doe murder victim after 40 years

SEATTLE - A decades long mystery out of Snohomish County has finally been solved.

Over 40 years ago, a killer came across a teenage girl near Silver Lake in Everett. The girl was hitchhiking. When she got into the killer's car, he made a sexual advance on her. She said no. Then, he murdered her. He didn't know who the girl was, and either did investigators when they found her body days later. The killer, David Roth, was caught and convicted, but the nagging mystery of who the victim was lingered on in the mind of a detective who refused to close the case.

"It struck my heart," says Detective Jim Scarf about the unidentified teen victim from the 1977 homicide. "I knew there's gotta be people out there who love her. She's precious to me, just like she must've been precious to them so that's why I named her Precious Jane Doe." Identifying Precious Jane Doe became a mission like no other for Jim. He signed every email with a plea to help ID her, he constantly searched missing person databases, and kept her case alive in the media. In 2013, Jim told Q13 News "It would really mean a lot to me to find the family that she belongs to and be able to tell them what happened to her."

And then, it finally happened. Jim got the call he'd been dreaming of. With the help of a paleontologist, using an innovative DNA extraction technique only ever used twice before, genetic genealogists were able to track down her half sister and brother.

"I always knew she was out there, and I always had hopes I'd find her," says Carol Holen, Lisa's sister. It's a sentiment shared by their brother, Ken Christensen. "It's hard to fathom what all I've missed in my life, and what she had to go through," says Ken.

Tracking down Precious Jane Does brother and sister was a huge break, but there was just one problem: she's been adopted as a baby, and her biological siblings, also adopted out, never met her. They knew she existed, but nothing else. "Here we are were coming to what we thought was going to be the conclusion, but it was really the beginning of a new mystery," says Detective Scharf.

Half sister Carol knew the challenges that went with tracking down Precious Jane Doe's adoptive family. "It was like a bread crumb trial that kept disappearing, but Jim stayed on it and I am extremely grateful for that."

Once again, Jim didn't give up. He finally found her adoptive family, which finally led to her name: Elizabeth "Lisa" Roberts of Oregon. The 17-year-old went by Lisa. Just as Jim suspected, her family never stopped looking for her. Now, Jim has connected her biological and adoptive family. They all plan to lay Lisa to rest together at a proper memorial service.

Half sister Carol says they owe it to the detective who refused to give up, "I don't think that anybody could do as good of a job. His experience, dedication, and the heart that the detective had-because it takes more than just knowledge, the heart is what came in to tie the whole family together."

Detective Jim Scharf says one of the heartbreaking aspects of this case is that Lisa Roberts was reported missing by her family in 1977, but law enforcement removed her from the missing person data system almost immediately. If they hadn't, Jim says Lisa would've been identified the day her body was found. If you have a loved one who was reported missing decades ago, he encourages you to reach out and make sure they're still in the system. It could be the missing piece that will finally bring them home.