The mystery surrounding the disappearance of the 84-year-old mother of NBC News anchor Savannah Guthrie has deepened, as the family and investigators continue to search for clues in the case. Nancy Guthrie disappeared in the middle of night from her home in Tucson, Arizona, last weekend and authorities believe she was taken against her will. Police in Arizona have not yet identified a person of interest in the suspected abduction and continue to investigate a series of apparent ransom notes that may have been sent from the person or people behind the alleged crime. The Guthrie family has made several public pleas for her safe return, and has asked for proof that their mother is still alive.