Pima County Sheriff Chris Nanos is sharing an update on their investigation into Nancy Guthrie‘s disappearance.

It’s now been almost 40 days since the 84-year-old mother of Savannah Guthrie was taken from her home in Arizona and in a new interview with NBC Nightly News on Thursday (March 12), the sheriff warned that that Nancy‘s abductor “could strike again.”

Keep reading to find out more…“Absolutely. We believe we know why he did this, and we believe that it was targeted, but we’re not 100 percent sure of that, so it’d be silly to tell people, ‘Yeah, don’t worry about it. You’re not his target,’” Sheriff Nanos said. “Don’t think for a moment because it happened to the Guthrie family you’re safe. Keep your wits about you.”

As for what the suspect’s motive might be, the sheriff remained coy.

“I think it’s come out from day one,” he said. “From day one, we had some strong beliefs about what happened, and those beliefs haven’t diminished.”

NBC Nightly News anchor correspondent Liz Kreutz noted in her report that the sheriff’s department is “intentionally withholding their theory and other details in the case, citing the integrity of the investigation.”

She also said that Nanos confirmed that investigators are looking into the reported internet outage in the area surrounding Nancy‘s home the night of her abduction and whether a wi-fi jamming device could have been used.

For the first time since her mother’s disappearance on February 1, Savannah returned to Today amid the ongoing search. Find out what she told her co-anchors…