The FBI did not publicly explain a full technical method for determining the Nancy Guthrie emails/notes were fake; reports say investigators concluded they were inauthentic, but the specific reasoning was not disclosed. One Reuters account says agents tested one message by depositing a small amount of cryptocurrency into the account it named, and the money was never withdrawn, which helped them decide that message was not genuine.

What was reported

  • Reuters said federal investigators deemed all three kidnapping-related messages fake communications, including two early ransom notes and a later message claiming to know the kidnappers’ identities.
  • Another report said the FBI’s Arizona office described some of the notes as “extortion attempts without legitimacy,” while still treating the overall case as a kidnapping-for-ransom investigation.
  • A Reuters-linked account says the agency’s crypto test was part of its authenticity check, but it did not reveal the full analysis behind the conclusion.

What remains unclear

  • The public reporting does not spell out whether the FBI relied on metadata, account tracing, writing analysis, device forensics, or other evidence.
  • Some outlets reported that the FBI had not explained exactly how it reached the judgment, and one source disputed Reuters’ framing of the notes.

Simple version

The best public answer is: the FBI appears to have used a mix of investigative checks, including a cryptocurrency test, and then concluded the messages were not legitimate, but it has not released the full method.

Information gathered from public reporting and portrayed here.