A government official said Monday that investigators probing the friendly fire death in Afghanistan of former football star Pat Tillman found no criminal negligence. The findings end a yearlong inquiry into the conduct of the U.S. soldiers who shot Tillman in 2004 and a possible subsequent cover up. The Army announced in March 2006 it would open a new investigation into the circumstances of Tillman's death, in response to complaints from Tillman's family and congressional representatives that previous probes had left key questions unanswered.