Article continues below advertisementAuthorities investigating Nancy Guthrie's disappearance are searching high and low for any information that leads to her whereabouts - which is why they even reportedly returned to a local restaurant she dined at months before she vanished from her Tucson, Ariz., home.NewsNation's Brian Entin claimed the FBI recently swung by the Mexican eatery where the 84-year-old and daughter Savannah Guthrie filmed a Today segment about hometowns.