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TUCSON, Ariz. – Authorities in Arizona confirmed late Sunday that they are searching for the mother of NBC "Today" co-host Savannah Guthrie, saying that a crime has been committed.

Nancy Guthrie, 84, was last seen Saturday evening at her residence near East Skyline Drive and North Campbell Avenue, north of Tucson, around 9:30 p.m., according to the Pima County Sheriff’s Department.

A relative of Guthrie’s contacted authorities around noon Sunday to report her missing, Pima County Sheriff Chris Nanos said.

"We’re pretty much just throwing everything at this that we can. Guthrie is 84 years old and is not of good physical health, and so naturally that’s a great concern," Nanos told reporters later Sunday, adding that the scene at the house raised "some concerns for us as well."

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Savannah Guthrie and mother Nancy Guthrie

Savannah Guthrie and mother Nancy Guthrie on Thursday, June 15, 2023. (Nathan Congleton/NBC via Getty Images)

"This is very concerning to us. We don’t typically get the sheriff out at a scene like this. But it’s very concerning what we’re learning from the house," Nanos said. "And so we’ll just continue. The detective’s homicide team is out right now looking at the scene as well."

During a news conference on Monday, Nanos said Nancy Guthrie's house is a crime scene and that she didn't leave on her own.

WATCH: Mom of NBC host Savannah Guthrie reported missing

"We believe now, after we processed that crime scene, that we do, in fact, have a crime scene that we do, in fact, have a crime," Nanos said. "She did not leave on her own. We know that."

While there was a search and rescue mission for Nancy Guthrie, Nanos said that has been shut down, saying: "We don't see this as a search mission as much as we do a crime scene."

Missing Person Nancy Guthrie

A missing person bulletin from the Pima County Sheriff's Department. (Pima County Sheriff's Department)

Nanos confirmed the woman is Savannah Guthrie’s mother. He said she is of "good sound mind" but has physical ailments that limit her mobility. Nanos added that someone from Nancy Guthrie's church called family members on Sunday morning to report she didn't show up. Nancy Guthrie's family went to her house and spent "some time" looking for her before calling 911, the sheriff said.

Media staging area for crime scene

Media staging area that is in proximity to a home that may be occupied by Nancy Guthrie, according to property tax records. (Fox News Digital/Christina Dugan Ramirez)

Guthrie

Savannah Guthrie visits "Fox & Friends" to discuss her new book "Mostly What God Does: Reflections on Seeking and Finding His Love Everywhere" at Fox News Channel Studios on Feb. 27, 2024, in New York City. (Roy Rochlin)

Authorities are using helicopters, infrared cameras and drones in the search for the missing 84-year-old. The sheriff has also enlisted help from Customs and Border Protection, NBC's Tom Winter reported.

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Savannah Guthrie released a statement to NBC's "Today" on Monday morning.

"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," the statement said.

WATCH: Sheriff's office deputies walk up driveway of house in area of Nancy Guthrie's house

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"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," it continued.