A ransom note sent days after the 84-year-old mother of US presenter Savannah Guthrie was abducted from her home claimed she had died.

The note was one of two addressed to Nancy Guthrie's family and sent to news media in the days after her January kidnapping. The first demanded millions in bitcoin for her release, but the second stated that she had died, according to sources cited by CBS, the BBC's US news partner.

The note from the possible kidnappers reportedly stated they did not mean for her to die and included an apology to the family.

The Pima County Sheriff's Department declined to comment on the contents of the notes but said the investigation "remains active and ongoing".

"The Pima County Sheriff's Department continues to work closely with the FBI as investigators follow up on leads, review information, and pursue the facts surrounding this case," a spokesperson for the sheriff's department said.

The BBC has contacted the FBI. The department, along with the FBI, has spent months investigating the elder Guthrie's mysterious abduction from her home near Tucson, Arizona.

It remains unclear if authorities believe the ransom notes are authentic, but the Guthrie family have stated they believe the letters, which were sent to local news media and national outlets like TMZ, were real.

Multiple outlets reported on Monday that law enforcement had requested they not publicise details from the notes as they investigated Guthrie's disappearance.

She was "taken in the dark of night from her bed", her daughter said, after last being seen on 31 January.

An initial ransom note was sent the day after she went missing and demanded millions in bitcoin for her release.

It gave specific details about her home, as well as details about her bedroom and the home's surroundings, investigators told CBS. The note was reportedly addressed to Savannah Guthrie, who is a co-anchor for the US news programme the Today show.

A second note - sent on 6 February - used language similar to that of the first note but did not include any demands, instead apologising for her death and stating it was inadvertent.

After the two notes, Savannah Guthrie and her siblings released a video appearing to respond.

"We received your message, and we understand," the NBC host said. "We beg you now to return our mother to us so that we can celebrate with her." She said the family "would pay".

Authorities and Guthrie's family repeatedly issued public warnings that the 84-year-old was in poor health and was without critical medication.

The Guthrie family had been offering a $1m (£760,000) reward, in addition to $100,000 pledged by the FBI, for information leading to Nancy's Guthrie's return.

On 24 February, Savannah Guthrie said they would keep hope even though they "know that she may be lost, she may already be gone".