NEW YORK - Four CBS News staffers were fired Monday following the release of an independent investigation that said a "myopic zeal" led to the airing of a discredited "60 Minutes Wednesday" story about President Bush military service. Moonves had appointed former Republican Attorney General Dick Thornburgh and Louis Boccardi, retired president and chief executive officer of The Associated Press, to investigate what went wrong and they delivered their report last week.Boccardi and Thornburgh said they could find no evidence to conclude the report — aired two months before Bush won re-election — was politically motivated.