Prosecutors say DNA evidence and family tree research will convict a man of double murder

EVERETT, Wash. -- A closely watched cold case murder trial in Snohomish County is about to go to the jury.

William Talbott, 56, is accused of killing 20-year-old Jay Cook and 18-year-old Tanya Van Cuylenborg in 1987.  Officials say Talbott was identified as a suspect using DNA found on a genealogy website.  On Tuesday, both sides rested their cases, and the prosecution says it is confident this new tactic in crime solving will work.

Investigators used the DNA to find relatives with a similar genetic makeup to find their suspect, but this is the first time that method is being tested in court.  Whatever happens has big ramifications for other cases, like the Golden State Killer. 

It’s something the defense called into question during Talbott's trial.

“There is no other evidence that was tested, and they tested everything in the van, that links to Mr. Talbott in any way,” said defense attorney Jon Scott.

Detectives say they collected Talbott’s DNA from the crime scene, uploaded it to a free online database of DNA samples, and then started building a family tree based on genetic matches.

“Some of those matches already have trees built on them or some of them give quite a bit information, or you can find information and then you’re basically just looking for a missing whole on a tree a missing limb,” said Family Discovered owner and genealogist Stephanie O’Connell.

Although some are trying to dispute the findings, O’Connell says it’s near impossible.

“The way you would try to dispute is say it’s somebody else, you’re looking at the wrong branch or you’re looking at the wrong line the wrong ancestral line.  That would be the only way,” said O’Connell.

One University of Washington Associate Professor says the crime-solving technique has other challenges.

“My relative can make a decision that can ultimately implicate me, and I have no say in the matter. So, there’s really important implications for informed consent,” said Associate Professor of Bio Ethics & Humanities at UW School of Medicine Malia Fullerton D. Phil.

The stakes are high in the Talbott case for a man accused of double murder and the families of both victims’ decades in the making.  They’re all wondering if the science behind genetic genealogy is good enough to hold up in court.

“Between the science and the straight records, you would have a pretty strong case,” said O’Connell.