Nancy Guthrie: DNA Expert Explains Why FBI Lab Testing Is Taking So Long

As the Nancy Guthrie investigation continues with no updates on potential suspects or DNA testing results, a forensic DNA expert has shared their thoughts on why it’s taking so long.

Nancy, the 84-year-old mother of Today‘s Savannah Guthrie, has been missing since February 1, when police believe she was abducted from her home in Tucson, Arizona. Investigators have released doorbell camera footage of a masked suspect and sent DNA for testing at the FBI lab in Quantico, but no suspects have been named.

Speaking to Anne Emerson on the Criminally Obsessed podcast, DNA expert Tiffany Roy, who has processed thousands of DNA samples and worked on thousands of cases, explained that testing can take a long time, especially if genealogy tracing is involved.

“There have been five different laboratories that have been involved in different stages of the testing of these samples,” Roy said on the DNA found in the Nancy case, per EconomicTimes. “So what happens when you have a case where you have DNA but you don’t know who it belongs to and you’ve searched it through the database, and we’re using all the tools at our disposal to try to put a name with that?”

“That can be very time-consuming,” she added, “especially if they’re in the genealogy process and if they have a sample that’s suitable for genealogy.”

Investigators found blood on Nancy’s front porch, but there has been debate about whether the blood belonged to Nancy, the suspect, or perhaps a mix of both.

“I know that they’ve discussed a mixed sample,” Roy continued. “And sometimes mixed samples are not going to be helpful for genealogy.”

Roy explained that genealogy testing is “the building of the trees and doing the research and working back through people’s genetic lines to try to link it with a family name and ultimately the name of an actual person. So, that research takes the longest time.”

Earlier this month, Pima County Sheriff Chris Nanos told People that the blood found at Nancy’s property could soon be identified. “I know we have DNA that is unknown who the contributor or depositor is, but I think they’re getting closer to finding out who that was,” he said, adding that he has “confidence in our labs.”

He continued, “When the labs tell us, ‘Hey, there’s nothing else we can do,’ well, then maybe we’ve got a problem… we’ve got a cold case… but right now, the labs aren’t telling us that.”