Some media outlets had previously reported receiving ransom notes tied to the case in the days after Guthrie's disappearance in early February from her home just outside Tucson, Arizona.
CNN reported on Monday that one of notes revealed that Nancy Guthrie was dead - and those who kidnapped her did not mean to kill her, but she died shortly after her disappearance.
CNN said it knew the contents of one such note and that a Tucson TV station had received two notes.
CNN and the station agreed to hold off on sharing the contents of the notes publicly so any future communications with the kidnapper or kidnappers could be authenticated.
The Pima County Sheriff's Department declined to comment on the note's contents.
The FBI didn't respond to a request for comment and the Guthrie family didn't make any immediate social media posts or any public comments about the notes.
Authorities believe Nancy Guthrie was kidnapped, abducted or otherwise taken against her will after finding blood near the doorstep of her home in the foothills outside Tucson.
The FBI later released surveillance videos showing a masked man on the porch that night.
Volunteers and search teams scoured the nearby desert terrain filled with cactuses, bushes and boulders in the weeks after she vanished.
A volunteer group recently conducted a search for her body near the Arizona-Mexico border but didn't report finding her.
