Article continues below advertisementInvestigators made mistakes early on in Nancy Guthrie's case, according to a former homicide sergeant.The 84-year-old mother of of Today star Savannah Guthrie has been missing for six weeks, with her disappearance reported on February 1. She was last seen the night before entering her secluded Tucson, Ariz. home, and authorities believe she is the victim of a "targeted kidnapping.