The search for Nancy Guthrie, the 84-year-old mother of TODAY show co-anchor Savannah Guthrie, entered its fifth day Thursday (February 5) as investigators continue to believe she was abducted from her Arizona home.

"Right now, we believe Nancy is still out there," Pima County Sheriff Chris Nanos said during a press conference Thursday. "We just want her home and find a way to get to the bottom of all of this."

The FBI announced it is now jointly investigating the case with the Pima County Sheriff's Department and has offered a $50,000 reward for information leading to Nancy Guthrie's recovery and/or the arrest and conviction of anyone involved in her disappearance.

FBI Phoenix Special Agent in Charge Heith Janke revealed there has been "no proof of life" since Nancy Guthrie disappeared. He also disclosed that an arrest has been made in connection with what he described as an "imposter ransom demand," with a criminal complaint expected to be presented to a judge later Thursday.

Authorities provided a timeline of Nancy Guthrie's disappearance, noting she was last seen Saturday night after being dropped off at her home in the Catalina Foothills area north of Tucson around 9:50 p.m. At 1:47 a.m. Sunday, her doorbell camera disconnected, and at 2:28 a.m., her pacemaker app showed a disconnection from her phone.

Sheriff Nanos confirmed that blood found on the porch of Nancy Guthrie's home "came back to Nancy," though he said investigators have "nobody of interest or any suspects that you would consider a prime suspect."

On Wednesday evening, Savannah Guthrie and her siblings released an emotional video plea for their mother's safe return, highlighting her fragile health condition.

"Our mom is a kind, faithful, loyal, fiercely loving woman of goodness and light," Savannah Guthrie said. "She lives in constant pain. She is without any medicine. She needs it to survive. She needs it not to suffer."

The family also addressed reports of ransom demands, saying: "We are ready to talk. However, we live in a world where voices and images are easily manipulated. We need to know without a doubt that she is alive and that you have her."

Anyone with information is urged to call 911 or the Pima County Sheriff's Department at 520-351-4900.

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