Some of the ransom notes sent to news outlets in the disappearance of Nancy Guthrie, the mother of NBC Today show anchor Savannah Guthrie, earlier this year were not legitimate, but other notes might be and are still under investigation, the FBI Phoenix office says.

Last month, Guthrie’s daughter and NBC anchor Savannah Guthrie delivered an emotional plea to viewers seeking information about her disappearance.

The FBI assessment of inauthenticity pertains to the two ransom notes reported in early February, and a third, more recent message.

An FBI official said the bureau believes the ransom notes sent to Nancy Guthrie's family are not genuine.