Arizona authorities announced they are investigating the disappearance of Nancy Guthrie, the mother of "TODAY" show co-anchor Savannah Guthrie, as a "crime."

"She did not leave on her own. We know that," Pima County Sheriff Chris Nanos said.

The 84-year-old was last seen Saturday night in her home outside Tucson and was reported missing by her family around noon Sunday. Nanos urged anyone with information to contact authorities.