Authorities investigating the disappearance of 84-year-old Nancy Guthrie have determined that a purported ransom note received over the weekend lacks credibility, according to the Pima County Sheriff’s Department in Arizona. Guthrie was last seen at her residence near Tucson on January 31 and reported missing the next day. Law enforcement officials continue to operate under the assumption that she was abducted or taken against her will. The case remains active as authorities pursue leads in their ongoing search for Guthrie.