A ransom note was sent to a local Arizona news station following the disappearance of "Today" show co-host Savannah Guthrie's mother, Nancy Guthrie, the Pima County sheriff has said.

The note, which the station received Monday and agreed not to report on, contained specific details about the home and what Nancy Guthrie was wearing that night, Pima County Sheriff Chris Nanos said, although he would not confirm the accuracy of that information or the legitimacy of the note.

"It's like any piece of evidence," Nanos told CBS News. "You give it to us, you give us a lead, we're going to look at every aspect of that lead."

Nanos did not specify which station the note was sent to, but CBS affiliate KOLD-TV reported Tuesday it had received an email that "appears to be one of the alleged ransom notes," which it forwarded to the sheriff's office.

Investigators have analyzed the note and are taking it seriously, Nanos said.

He said the FBI reviewed the note and made the decision to share it with Savannah Guthrie. Authorities had hoped to keep the information from becoming public, but the note was obtained by TMZ, which reported on it before contacting the sheriff's office, Nanos said.

The Pima County Sheriff's Department had earlier said on social media it was aware of "reports circulating about possible ransom note(s)," adding, "Anything that comes in, goes directly to our detectives who are coordinating with the FBI."

Surveillance video from a home security system has yielded nothing so far, Nanos told CBS News. He said investigators believe the system may have been set to automatically delete footage after a short period of time, and they are now attempting to recover it through forensic means.

Nanos previously told CBS News that investigators believe the 84-year-old was abducted from her home in the middle of the night over the weekend, and he described it as "a crime scene." Authorities have been searching for her since Sunday.

Nancy Guthrie was last seen at her home Saturday night, but no one knew she was missing until she didn't show up for church the next morning, Nanos said.

The sheriff has repeatedly said Guthrie, who lives alone, could not have wandered away from her home because she has no cognitive issues and very limited mobility.

He also expressed concern that she needs access to medication that she must take daily, telling CBS News, "The clock is literally ticking."

"You've placed her in great jeopardy without giving her meds that are critical to her," Nanos said. "Again, like I've said, could be fatal if she doesn't get those meds."

The sheriff has said it's unclear how many people may have been involved in the apparent abduction.

"It could be one, it could've been more, I don't know," he said.

A little bit of blood was found inside Nancy Guthrie's Tucson home, a law enforcement source familiar with the case told CBS News, and what appeared to be a small amount of dried blood was seen next to a doormat outside the front door of the home on Tuesday.

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