A new message about Nancy Guthrie, the mother of journalist Savannah Guthrie, co-anchor of NBC's 'TODAY' show, who disappeared six days ago, was sent this Friday to a television station in Arizona.

Tucson television station KOLD reportedly received an email about the woman's case 84 years old, according to sources cited by NBC News.

The FBI is working to confirm if the note came from the same sender as an earlier ransom note that referenced Guthrie.

This Friday marks the sixth day that Guthrie's whereabouts have been unknown. She was last seen Saturday night, January 31, at her home north of Tucson.

The FBI offered a reward of up to $50,000 on Thursday for information leading to finding the woman or to the arrest and conviction of anyone involved in her disappearance.

Authorities have warned that Guthrie is considered a "vulnerable adult" with difficulty walking, who uses a pacemaker and needs daily medication for a heart condition.

Since the investigation began, police have treated the case as a homicide after Guthrie's doorbell camera disconnected, software detected a person's presence, and the pacemaker app was triggered.

Guthrie's phone showed that he had disconnected. Furthermore, evidence of forced entry was found at the residence located in the Catalina Foothills neighborhood, in the middle of a desert area north of Tucson. The case has sparked much speculation, and at least three alleged ransom notes were reportedly sent to media outlets before the one sent this Friday. The FBI reported this Thursday that one person has been arrested in connection with a "fraudulent ransom lawsuit."