Article continues below advertisementDetectives working tirelessly to find Savannah Guthrie's missing mom, Nancy Guthrie, are stumped in terms of the motive of her alleged kidnappers. Pima County Sheriff Chris Nanos told an outlet on Monday, February 16, that investigators are having trouble determining why the 84-year-old was taken from her Tucson, Ariz., home in the middle of the night more than two weeks ago.