Savannah Guthrie's mother, Nancy Guthrie, missing in Arizona; sheriff calls her home a crime scene

The disappearance of "Today" show host Savannah Guthrie's mother, Nancy, is being treated as a crime, police in Arizona said Monday, as they urged neighbors to review home video camera footage.

"We saw some things at the home that were concerning to us," Pima County Sheriff Chris Nanos told reporters Monday. "We believe now after we've processed that crime scene that we do in fact have a crime scene, that we do in fact have a crime, and we're asking the community's help."

Nanos urged people who think they see Nancy Guthrie to take a picture or record a video and alert authorities. A missing person's flier from the sheriff's department said she is 5 feet, 5 inches tall, has brown hair and blue eyes and weighs 150 pounds.

Nancy Guthrie "is very limited in her mobility" and "we know she didn't just walk out of there," Nanos said, adding that there are other aspects at the scene which indicate she did not leave on her own.

She doesn't have any cognitive issues, but is in urgent need of her daily medication, authorities said. Nanos said she lived by herself.

"I want to stress to you, and it is really important: Miss Guthrie, Nancy Guthrie is of great sound mind," Nanos said. "This is not a dementia-related, she is as sharp as a tack. The family wants everybody to know this isn't somebody who just wandered off."

Nanos didn't provide additional details about what investigators found concerning at the home, citing the ongoing investigation. Sgt. David Stivers told reporters, "There were circumstances on scene that we believe are suspicious in nature, I think is the best way to put it."

The FBI is assisting in the investigation, two sources told CBS News.

The search and rescue team worked through the night, employing drones, helicopters and heat sensors, but have since been sent home, Nanos said, as the search has turned to a criminal investigation. "Right now we don't see this as a search mission so much as we do a crime scene," he said.

Investigators were poring over footage from security cameras in the home and examining Nancy Guthrie's cellphone, Nanos said. Authorities were also turning to license-plate readers and other surveillance cameras for leads in the case. The sheriff encouraged Guthrie's neighbors to go through their own home security footage, even if their cameras don't face the Guthrie home.

"They still might see something," Nanos said. "Maybe it's somebody walking by. Maybe it's some vehicle driving by at that time of day."

The sheriff said investigators didn't know if Guthrie was targeted. He also said he didn't think that there was an active threat that posed a danger to the public.

Nanos said the family was cooperating with the investigation.

Savannah Guthrie issued a statement on her mother's disappearance Monday.

"On behalf of our family, I want to thank everyone for the thoughts, prayers and messages of support," she said. "Right now, our focus remains on the safe return of our dear mom."

Guthrie urged anyone with information to contact the Pima County Sheriff's Department.

Nanos said Nancy Guthrie was last seen at her home in the Catalina Foothills area at 9:30 p.m. Saturday. When she didn't show up for church the next morning, family members went to her home, looked for her and called 911, Nanos said.