The Pima County Sheriff's Office in Arizona has released two ransom notes as part of an ongoing investigation into the abduction of Nancy Guthrie, the mother of US news presenter Savannah Guthrie. Police are hoping the public can identify the perpetrator by recognizing "distinct linguistic characteristics" present in the notes.

Nancy Guthrie, 84 at the time of her disappearance, was taken from her home near Tucson on January 31. The Sheriff's Office stated the investigation remains active and they cannot verify a claim made in one of the notes that she died shortly after her abduction.

Two notes were sent to a local TV station in Tucson in the days following her disappearance and were addressed to Savannah Guthrie and the Guthrie family. Investigators released them on Friday.

The first note, received on February 2, demanded millions of dollars in Bitcoin for Nancy Guthrie's safe return. "She is safe but scared," the note read. "She will be held for ransom and once payment is received she will be released unharmed."

The note outlined a deadline of 5 p.m. on Thursday, February 5, for a $4 million USD payment in Bitcoin. It warned that if payment was not received, the ransom would increase to $6 million USD, with a new deadline of 5 p.m. on Monday, February 9. The writer stated that if the final deadline was missed, Nancy Guthrie would be killed. The note also specified that law enforcement intervention was not advised and no negotiation would occur.

Following a redacted sentence, the note concluded with observations about items in the home: "She had a white smart watch on the floor of the foot of her bed and the white flood light in backyard was destroyed."

The second note, which claimed Nancy Guthrie had died shortly after her abduction, has not been verified by authorities. The Sheriff's Office urged anyone who might recognize the writing style or have any information to come forward, stating that "a friend, family member, coworker, classmate, or acquaintance may recognise these patterns of expression and possess information that could help identify the individual responsible."

Officials have not shared a possible motive for the abduction or announced any suspects. The Pima County Sheriff's Office has stated that Nancy Guthrie's life is in the hands of the abductor and that cooperation is expected to be swift.