A strand of DNA recovered from Nancy Guthrie’s Arizona home is undergoing extensive testing at the FBI’s crime lab as the investigation hit the 100-day mark — and authorities continue to hold out hope for a break in the case.

The FBI was shut out of the Nancy Guthrie investigation for the first four days after the mother of the "Today Show" host, Savannah Guthrie went missing, FBI Director Kash Patel claimed in a new interview. "For four days, we were kept out of the ...