Savannah Guthrie’s family is “at a desperate hour” in the search for her missing mother, Today the show’s co-host said in a video released Monday ahead of an upcoming ransom deadline apparently set by Nancy Guthrie’s kidnappers.

Savannah Guthrie did not mention a deadline in the video, saying her family still believes their 84-year-old mom is out there hearing everyone’s prayers.

“She’s been taken and we don’t know where, and we need your help,” Guthrie said in a video posted on Instagram that urged people across the country 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,” she said.

“We are in an hour of desperation,” she said.

The mysterious disappearance and search has taken the US by storm – from President Donald Trump speaking with Savannah Guthrie last week to internet detectives flooding social media with tips, theories and rumours.

Several news outlets have received alleged ransom letters over the past week. At least one letter contained monetary demands and set deadlines for receiving the money. The first deadline expired last Thursday, but the second was set for Monday evening.

Law enforcement officials declined to confirm the letters were credible, but said all tips are being investigated seriously.

WATCH | Who Took Nancy Guthrie?:

Who Kidnapped Savannah Guthrie’s Mother? | About that

Five days into the search for Nancy Guthrie — the mother of Today show host Savannah Guthrie — police who believe she was abducted from her Tucson home are facing more questions than answers. Andrew Chang breaks down what we know about the timeline of Guthrie’s disappearance, possible ransom deadlines and why time is running out. Images provided by The Canadian Press, Reuters, Getty Images and Adobe Stock

Authorities say they are concerned about Nancy Guthrie’s health because she needs daily medication. She is said to have a pacemaker and has had high blood pressure and heart problems, according to audio from sheriff’s dispatchers on broadcastify.com.

Investigators returned to Nancy Guthrie’s Arizona neighborhood several times over the weekend ahead of a Monday night deadline set by her alleged captors who sent ransom messages demanding money for her return.

Savannah Guthrie said over the weekend that the family is willing to pay for her mother’s return.

“Now we are asking you to give us back our mother so we can celebrate with her,” she said in a video released on Saturday. “This is the only way we will have peace. This is very valuable to us and we will pay.”

WATCH | The family is willing to pay:

Savannah Guthrie says the family is willing to pay the would-be kidnappers a ransom for her mom’s return

NBC anchor Savannah Guthrie told the would-be kidnappers of her mother, Nancy Guthrie, on Saturday that the family is willing to pay for her safe return.

There are no suspects, no persons of interest

Authorities say they believe Nancy Guthrie was taken against her will from her home near Tucson. She was last seen there on January 31 and was reported missing the next day after she failed to attend a church service. DNA tests showed blood on Guthrie’s front porch matched her and that her doorbell camera was turned off early Sunday morning, Pima County Sheriff Chris Nanos said.

Outside the home Monday, neighbors were out for their morning jogs and walks as a county sheriff’s deputy remained stationed outside.

Detectives and agents conducted further 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 associated with this case,” the department said.

On Saturday, investigators were at the house of Annie Guthrie’s daughter, about six kilometers from Nancy Guthrie’s house. On Sunday, an investigator was seen using a pole to search an underground storage tank behind Nancy Guthrie’s home.