There is evidence of a crime at the home of the missing 84-year-old mother of “Today” show host Savannah Guthrie, according to authorities in Arizona.

Nancy Guthrie was last seen in the Catalina Foothills area on Saturday night, according to the Pima County Sheriff’s Department. Her family reported her missing on Sunday around noon local time, authorities said.

Pima County Sheriff Chris Nanos said investigators processed her home on Sunday and “saw some things at the home that were concerning to us,” and that it is considered a crime scene.

“She did not leave on her own, we know that,” Nanos said during a press briefing on Monday.

Nancy Guthrie is described as having some physical ailments and limited mobility, but does not have cognitive issues, her family said, according to the sheriff.

She takes medication that if she doesn’t have in 24 hours, “it could be fatal,” Nanos said Monday.

“So we make a plea to anyone that knows anything about this, who has seen something, heard something, to contact us, call 911,” he said, urging residents to check any home security cameras.

The search and rescue effort for Nancy Guthrie, which was conducted late into Sunday night “to no avail,” has ended for the time being, Nanos said.

“Right now, we don’t see this as a search mission, as much as we do a crime scene,” he said.

The FBI said it is assisting in the investigation.

There’s no indication at this time that the public is in danger, authorities said.

Nancy Guthrie was last seen Saturday night by family members, Nanos said. Her children brought her home, where she lives alone, around 9:45 p.m. local time, according to Nanos. The following morning, her family got a call from their mother’s church saying she wasn’t there, he said.

“The family went to the house. I’m thinking they spent some time looking for her themselves before they called us,” he said.

Investigators found “circumstances on scene that we believe are suspicious in nature,” Sgt. David Stivers from the sheriff’s department’s homicide team, said during the press briefing Monday, though he did not go into further detail.

Authorities said they are reviewing the home’s security cameras and have Nancy Guthrie’s cellphone.

It is unclear if this was targeted, Nanos said. When asked whether Savannah Guthrie has received any threats, the sheriff said his department has been in touch with her security team and is unaware of any such threats at the moment.

“We’re not going to dismiss any angles for sure, but right now, immediately, we don’t know of anything like that,” Nanos said.

An NBCUniversal spokesperson confirmed early on Monday that Nancy Guthrie is missing and said the family is “working closely with local law enforcement.”

“On behalf of our family, I want to thank everyone for the thoughts, prayers and messages of support,” Savannah Guthrie said in a statement read by Craig Melvin on the “Today” show on Monday. “Right now, our focus remains on the safe return of our dear mom.”

“We thank law enforcement for their hard work on this case and encourage anyone with information to contact the Pima County Sheriff’s Department at 520-351-4900,” the statement continued.

ABC News’ Cecilie Larcher contributed to this report.