All three kidnapping-related messages that have surfaced in media reports about the disappearance of NBC Today show host Savannah Guthrie's mother are fake, an FBI official says. The FBI assessment pertains to the two ransom notes reported in early February, days after 84-year-old Nancy Guthrie went missing, and a third, more recent message from someone claiming to know the kidnappers' identities, the official said."None of the ransom notes are believed to be genuine," the FBI official told Reuters, speaking on condition of anonymity.A second law enforcement source familiar with the matter confirmed the FBI's assessment.Nancy Guthrie's daughter, Savannah, says the family is "blowing on the embers of hope". (Reuters: Rebecca Noble)The disclosure seems to raise doubts about the premise that Nancy Guthrie was abducted for ransom.A spokesperson for the Pima County Sheriff's Department, which is leading the overall investigation, declined to comment, citing its agreement to refer all inquiries regarding ransom notes to the FBI."We don't have any updates, other than this is still an active investigation," Angelica Carrillo said. She added that DNA samples and video evidence collected in the case remained "under forensic analysis".All three messages in question were delivered to media outlets, including celebrity news site TMZ, before they were turned over to authorities for review.Savannah Guthrie, 54, has referenced ransom demands in video messages she and her siblings have posted on social media.She has urged kidnappers to open a direct line of communication with her family and pleaded for her mother's return, saying in one video, "we will pay".Cryptocurrency payment not takenThe elder Guthrie, who had been in frail health with limited mobility, was last seen at her home in Tucson, Arizona, on January 31, after spending an evening with her older daughter, Annie Guthrie, and her son-in-law.The FBI, which has taken the lead in examining purported ransom notes or other communications from suspects in the case, had previously declined to say publicly whether any of the messages under review were considered credible.Nancy Guthrie's home in Tucson, Arizona. (Reuters: Rebecca Noble)Investigators determined that the first two originated from the same sender, the official told Reuters, though how that conclusion was drawn was not specified.The first note, according to TMZ, demanded a sum "in the millions" to be paid in cryptocurrency by February 5 and February 9.The second note was reported by NBC News last week to have referred to Nancy Guthrie as having died. There was no demand of payment for the return of her body.In a bid to test the authenticity of the first note and possibly trace the ransom demands back to the perpetrators, the FBI deposited a small amount of cryptocurrency in an account as instructed in the message, but the money was left untouched in the account, the official said.On that basis and by other unspecified means the FBI reached the conclusion that the two ransom notes, determined to be of a common origin, were not sent by anyone connected with Nancy Guthrie's disappearance, the official said.The FBI has additionally discounted the authenticity of a third note TMZ reported it received last week from someone claiming to know the identities of Nancy Guthrie's abductors and to have video of the "main guy" involved in her kidnapping, as well as of the victim on the day she died.The FBI official did not reveal how investigators ruled out the third note as fake.Reacting to last week's ransom note headlines, Savannah Guthrie took time on her show to appeal to the public again for answers to the fate of her mother, urging anyone who might know something to come forward.She also reminded viewers of the $US1 million ($1.45 million) reward being offered by her family, whom she described as being in "agony" since her mother vanished.Authorities confirmed soon after her disappearance that DNA tests showed that blood found on Nancy Guthrie's front porch came from her.Media attention on the case has waned considerably since mid-February, when the sheriff and FBI released surveillance footage of an armed prowler in a ski mask shown tampering with Nancy Guthrie's doorbell camera shortly before she was abducted.But DNA samples obtained from a glove found near her home and resembling the pair the prowler was seen wearing failed to produce a match with genetic profiles in a national database.Savannah Guthrie later said her family was still "blowing on the embers of hope" but acknowledged that her mother "may already be gone".Reuters