Disappearance of mother of Savannah Guthrie, NBC News anchor, investigated as a crime

The disappearance of the mother of US news anchor Savannah Guthrie is being investigated as a crime, and her home is now considered a crime scene, officials in Arizona said on Monday.

Nancy Guthrie, the 84 year-old mother of the NBC News host, was last seen in her home outside Tucson, Arizona, on Saturday evening.

Her family reported her missing a day later. When authorities arrived, Pima County Sheriff Chris Nanos said, the scene of Nancy Guthrie's home caused "grave concern". An intense search followed, which Nanos said has since been paused while officials look into the possibility of a crime being committed against her.

"She did not leave on her own, we know that," Nanos said.

Nanos offered very few details about what he said was still a "very active" investigation, and urged the public to call authorities with any information. It is not clear what at her home led authorities to develop grave concerns.

The Guthrie family previously said in a statement to NBC News: "We can confirm this is a missing persons case, and the family is working closely with local law enforcement."

Searchers were sent home on Monday to rest after looking all night for Nancy Guthrie, who is described as "not in good physical health" but also has no reported cognitive issues, according to Nanos.

They used drones, aircraft, helicopters, heat sensors, and infrared, he said, sadding: "Everything we have, we've thrown at this."

In an earlier press conference, Nanos had said homicide detectives were called to the scene, which he said was not standard protocol in a missing persons case. He also said foul play could not be ruled out.

Nancy Guthrie was last seen at her home after 21:00 local time on Saturday (04:00 GMT on Sunday), Nanos said.

Savannah Guthrie, who hosts the Today show, was not on air on Monday morning.

But her colleagues shared a statement from her, which said: "On behalf of our family, I want to thank everyone for the thoughts, prayers and messages of support.

"Right now, our focus remains on the safe return of our dear mom."