Savannah Guthrie makes new video plea as missing mother's ransom deadline nears

"She was taken and we don't know where, and we need your help," Guthrie said in the video posted on Instagram that urged people nationwide to be on the lookout. "No matter where you are, even if you're far from Tucson, if you see anything, if you hear anything."

"We are at an hour of desperation," she said.

The mysterious disappearance and search has riveted the U.S. — from President Donald Trump who spoke with Savannah Guthrie last week to the online sleuths who've flooded social media with tips, theories and rumors.

Multiple press outlets have received alleged ransom letters during the past week. At least one letter made monetary demands and set deadlines for receiving the money. The first deadline passed last Thursday but a second one was set for Monday evening.

Law enforcement officials declined to affirm that the letters were credible but said all tips were being investigated seriously.

Authorities say they have growing concerns about Nancy Guthrie's health because she needs daily medication. She is said to have a pacemaker and has dealt with high blood pressure and heart issues, according to sheriff's dispatcher audio on broadcastify.com.

Investigators returned to Nancy Guthrie's Arizona neighborhood several times over the weekend, ahead of a Monday evening deadline set by her purported abductors who sent ransom notes demanding money for her return.

Savannah Guthrie said over the weekend that the family was prepared to pay for her mother's return.

"We beg you now to return our mother to us so that we can celebrate with her," she said in a video posted Saturday. "This is the only way we will have peace. This is very valuable to us, and we will pay."

Authorities believe Nancy Guthrie was taken against her will from her home just outside Tucson. She was last seen there on Jan. 31 and reported missing the next day after not attending church services. DNA tests showed blood on Guthrie's front porch was a match to her and her doorbell camera was disconnected in the early hours of Sunday morning, Pima County Sheriff Chris Nanos has said.

Outside the home on Monday, neighbors strolled by on their morning jogs and walks, while a county sheriff's deputy remained stationed out front.

Detectives and agents carried out follow-up work at multiple locations over the weekend as part of the investigation, the Pima County Sheriff's Department said Sunday. "Investigators have not identified any suspects, persons of interest, or vehicles connected to this case," the department said.

Investigators on Saturday were inside daughter Annie Guthrie's home, about 4 miles (6 kilometers) from Nancy Guthrie's house. On Sunday, an investigator was seen using a pole to search an underground tank behind Nancy Guthrie's home.