Investigators in the disappearance of “Today” show co-host Savannah Guthrie’s mother, Nancy Guthrie, haven’t identified a suspect or person of interest in the Arizona case, which is being investigated as a crime, authorities said Wednesday.

The Pima County Sheriff’s Department posted the update to social media as the search continues for Nancy Guthrie, 84, who was reported missing Sunday.

“Detectives continue to speak with anyone who may have had contact with Mrs. Guthrie,” the sheriff’s department said in Wednesday’s statement.

Authorities believe Guthrie was taken from her Tucson, Arizona, home over the weekend. A little bit of blood found inside the home was being tested, a law enforcement source familiar with the case told CBS News.

“Detectives are working closely with the Guthrie family,” the sheriff’s department said in its statement Wednesday. “While we appreciate the public’s concern, the sharing of unverified accusations or false information is irresponsible and does not assist the investigation.”  

Pima County Sheriff Chris Nanos said Tuesday that evidence collected from the home hadn’t yet pointed toward a suspect. He also said it wasn’t clear how many people took Guthrie. “It could be one, it could’ve been more, I don’t know,” he said.

The department said detectives were working closely with Guthrie’s family, who reported the disappearance to authorities Sunday after looking for her at her home when they were told that Guthrie missed church.

Nanos told CBS News on Tuesday that a ransom note was sent to a local Arizona news station following Guthrie’s disappearance.

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

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.

Earlier this week, Nanos told Us Weekly that Guthrie’s other daughter, Annie Guthrie, was the last known person to see her mother before the disappearance. The sheriff said Nancy Guthrie was dropped off at her home after dinner Saturday night.

Nanos has dismissed the possibility that Nancy Guthrie, who lives alone, may have wandered away from her home because he said she doesn’t have any cognitive issues and her mobility is limited.

Nancy Guthrie has three children in total: Annie Guthrie, Savannah Guthrie and son Charles Guthrie.