FBI says it arrested a 'total imposter' for trying to profit off Nancy Guthrie's disappearance with a bogus ransom

• The FBI has made an arrest related to an "imposter ransom demand" involving Savannah Guthrie's mom.
• Police believe Nancy Guthrie was taken from her Arizona home five days ago.
• Authorities said they are taking a separate ransom letter distributed to the media "seriously."

The FBI has arrested what an official called a "total imposter" for allegedly trying to profit off the mysterious disappearance of "Today" show host Savannah Guthrie's mother with a bogus ransom note.

FBI Phoenix's special agent in charge, Heith Janke, said at a press conference over the disappearance of 84-year-old Nancy Guthrie that the arrest was related to an "imposter ransom demand" for the woman, who authorities believe was taken from her Arizona home five days ago.

Additional details surrounding the arrest were not immediately available.

"To those imposters who are trying to take advantage and profit from this situation, we will investigate and ensure you are held accountable for your actions," Janke said.

Janke also issued a message to anyone who may be involved in Nancy Guthrie's disappearance, urging them to "do the right thing."

"This is an 84-year-old grandma that needs vital medication for her well-being," Janke said. "You still have the time to do the right thing before this becomes a worse, much worse scenario for you."

The FBI is offering a reward of up to $50,000 for information leading to the recovery of Nancy Guthrie and/or the arrest and conviction of anyone involved in her disappearance, Janke announced.

Authorities said that an additional ransom letter regarding Nancy Guthrie, sent to local and national media outlets, is being taken "seriously."

That note made a monetary "demand" for 5 p.m. local time Thursday, said Janke.

"If a transfer wasn't made, then I think a second demand was for next Monday," Janke said, declining to provide other specifics.

An Apple Watch and a floodlight were also mentioned in ransom letters, Janke said.

"We're not going to go into specifics. It's very important that we keep this investigation moving forward, and we don't want to put more facts out there that others then can use to try to profit from this," he said.

Nancy Guthrie was reported missing by her family on February 1, and local authorities have said that they believe the elderly woman, who was limited in her mobility, was taken from her home "against her will."

She suffers from physical ailments and requires daily medications that, if not taken every 24 hours, could have life-threatening consequences.

"Right now, we believe Nancy is still out there. We want her home," Pima County Sheriff Chris Nanos said during the Thursday press conference.

Authorities revealed new details around the timeline of Nancy Guthrie's disappearance on Thursday and confirmed that the blood discovered on the elderly woman's porch belonged to her.