TUCSON, Ariz. — Five months after Nancy Guthrie vanished from her Tucson home, leaving behind her medication, wallet and cellphone, federal investigators are still pursuing the case as a kidnapping for ransom, one arrest has been made in connection with fraudulent communications, and experts outside the investigation are increasingly skeptical that any of the ransom notes publicly reported so far are genuine.

The 84-year-old mother of "Today" show co-anchor Savannah Guthrie disappeared in the early hours of February 1 after being dropped off at her Catalina Foothills home the previous evening. Blood found on her front porch was confirmed by DNA testing to belong to her. Surveillance footage recovered from corrupted camera data showed a masked individual tampering with her doorbell camera that night. Her pacemaker app disconnected from her phone at 2:28 a.m., a timestamp investigators believe may correspond to when she was forcibly removed from the home.

Despite that physical evidence, no suspects or persons of interest have been publicly named in connection with the actual disappearance, and the investigation now enters its sixth month without a confirmed account of what happened or where Guthrie is.

Criminal defense attorney and trial lawyer Mark Geragos told NewsNation's "Cuomo" program that he believes the FBI has consolidated its control over the investigation and that any breakthrough is most likely to come from inside the alleged criminal network rather than from external tip lines or media pressure.

"The FBI now, I think, has pretty firm control over the investigation, and they believe at this point that if it's going to be........

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