1 MINUTE AGO: The police chief unexpectedly announced: Savannah Guthrie’s mother’s house is the “crime scene” — and she didn’t leave as everyone thought. The detail was discovered thanks to a single object in the corner next to the cabinet where she usually kept her medication….

The Pima County Sheriff’s Department held a press conference on Monday, Feb. 2, as Savannah Guthrie’s mom remains missing.

Nancy Guthrie disappeared on Saturday, Jan. 31, and the PCSD launched an urgent search for the 84-year-old the following day. At the press conference, Sheriff Chris Nanos said that “time is very critical” as Nancy lacked physical mobility and the scene showed signs that a crime had taken place.

“This is an 84-year-old lady who suffers from some physical ailments, has some physical challenges, is in need of medication — medication that, if she doesn’t have in 24 hours, it could be fatal,” Nanos revealed. “So we make a plea to anyone who knows anything about this, who has seen something, heard something, to contact us. Call 911. We don’t we don’t need another bad, tragic ending. We need some help.”

He said they spent “a lot of resources” in their search and rescue efforts, including using volunteers “and other agencies” who “worked tirelessly all day yesterday and all last night to no avail.”

He continued, “As I said yesterday, we saw some things at the home that were concerning to us. 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 shared that they have reason to believe that Nancy was “of great sound mind” and “did not leave on her own,” adding teams have been working through the night to review security camera footage, license plate readers and conduct searches.

“We’ve not just thrown our search and rescue team out there,” he explained. “They’re going to be doing some door-to-door with our Criminal Investigation Team. It is not just our Homicide Unit — all of our criminal investigation detectives. I went out last night to the scene. There were probably 100 cars out there, all from the Sheriff’s Department, all working this case. It takes a lot of manpower and a lot of energy.”

He also confirmed that Savannah is in Arizona and the entire family has been “cooperative” with investigators, further noting that they have elicited the help of other agencies such as the FBI.

“It’s still very active investigation,” Nanos concluded in part. “There were circumstances on scene that we believe are suspicious in nature, I think is the best way to put it.”

When asked by a reporter why it’s labeled as a crime scene, Nanos explained, “She is very limited in her mobility, right? We know she didn’t just walk out of there. We know there are other things at the scene that indicate she did not leave on her own.”

Nancy was last seen at her Arizona residence near East Skyline Drive and North Campbell Avenue at around 9:30 p.m. local time.

Savannah, 54, skipped the Today show on Monday, Feb. 2, as her mother remained missing. Sheinelle Jones filled in for Guthrie alongside Craig Melvin, who told viewers during the broadcast, “We want to get right to what is a deeply personal story for us, Nancy Guthrie, Savannah’s beloved mother, has been reported missing in Arizona.”

Savannah also released a statement to the Today show, as she 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.”

“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.”

Shortly after the news broke, Nanos revealed that the search-and-rescue mission is underway amid a concerning scene at Nancy’s house after family called 911 around noon to report her missing.

“We get these calls quite often, and we do a good job of searching the area,” he said. “But, this one stood out because of what was described to us at the scene and what we found and located just in looking at the scene.

Nanos added that the mother of the Today show co-anchor is considered “not in good physical health” and may have been exposed to cold weather all night, but confirmed Nancy has “no cognitive issues at all, just some physical ailments that limit her ability to move around.”

A spokesperson for Today said in a statement to PEOPLE, “We can confirm this is a missing persons case, and the family is working closely with local law enforcement. If anyone has any information, please contact the Pima County Sheriff’s Department at 520-351-4900. The family is grateful for the outreach, thoughts and prayers.”

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human interest stories.

The PCSD describes Nancy, 84, as a female with brown hair and blue eyes. She is 5 feet, 5 inches tall and weighs around 150 lbs. It is currently unknown what clothes she was wearing at the time of her disappearance.

The Pima County Sheriff’s Department encourages anyone with information to get in touch at 520-351-4900.