The Pima County Sheriff's Department said investigators are "working around the clock" as the search for Nancy Guthrie, the missing 84-year-old mother of Today show host Savannah Guthrie, continues. The sheriff's department said on Wednesday that it is working alongside the FBI to follow up on all leads. "We thank the media and the public for the thousands of tips submitted through the various tip lines. PCSD alone has received nearly 18,000 calls since February 1—more than 4,000 of those in