A DNA expert says the genetic evidence found in the Nancy Guthrie kidnapping case could present significant challenges for investigators, even as the search for the missing Arizona woman continues.
Guthrie, the mother of Today Show journalist Savannah Guthrie, was abducted from her Arizona home almost three weeks ago. Investigators say DNA found on a glove at the scene has not matched anyone in the national database, but experts say that doesn't mean the case has stalled.
WATCH | Hampikian on the Nancy Guthrie Kidnapping—
Greg Hampikian, a Boise-based forensic DNA expert and founder of the Idaho Innocence Project, explained how mixed DNA samples can complicate investigations. Hampikian has worked on wrongful conviction cases across the country, including helping overturn Amanda Knox's conviction.
"For the genealogist, really, if it's more than 2 people in that mixture, they have a real problem," Hampikian said.
DNA from a glove, like in the Guthrie case, can be especially challenging when it contains genetic material from more than one person.
"When it's more than one person, it's hard to tell whose peaks go together, and you just get a bunch of jumbled information," Hampikian said.
Even without a match in CODIS — the nationwide database linking forensic evidence to DNA profiles from offenders, arrestees, and missing persons — investigators can turn to genetic genealogy. That method analyzes hundreds of thousands of genetic markers to identify potential relatives of a suspect and build out family trees.
"That first person you have is not necessarily a perfect match. It's just a suspect," Hampikian said. "So it can take, it can take that part can take months, you know."
Genealogy isn't perfect. Errors in family trees, adoptions, or limited ethnic representation in databases can slow progress. One thing DNA cannot tell investigators is when it was left behind.
"There's no way to tell when DNA got there or how it got there," Hampikian said.
As the search continues for Nancy Guthrie, some wonder why the case hasn't moved faster. Hampikian says kidnappings and complex investigations rarely unfold overnight.
"The pacing of this case is not off, you know, it's being pursued really heavily and by some very qualified people. It's hard to solve a kidnapping," Hampikian said.
