"An hour of desperation": Savannah Guthrie asks for public's help

State of play: The Pima County Sheriff's Department said on Sunday that it has not identified a suspect or person of interest in the case.

Catch up quick: Guthrie was last seen on Jan. 31 when a family member dropped her off at her Catalina Foothills home. She was reported missing the following day.

• Over the weekend, Guthrie and her siblings recorded a video addressing the sender of the ransom demand, saying "We received your message and we understand ... this is very valuable to us, and we will pay."

The latest: In a separate video posted to Instagram on Monday afternoon, Guthrie thanked her followers for their prayers and asked once more for assistance in finding her mother.

• "Even if you're far from Tucson, if you see anything, if you hear anything, if there's anything at all that seems strange to you ... report to law enforcement. We are at an hour of desperation and we need your help," she said.

The bottom line: "We believe our mom is still out there," Guthrie said. "Law enforcement is working tirelessly around the clock trying to bring her home, trying to find her. She was taken and we don't know where and we need your help."