Four CBS News employees, including three executives, have been ousted for their role in preparing and reporting a disputed story about President Bush’s National Guard service. The action was prompted by the report of an independent panel that concluded that CBS News failed to follow basic journalistic principles in the preparation and reporting of the piece. The panel also said CBS News had compounded that failure with a “rigid and blind” defense of the 60 Minutes Wednesday report. Asked to resign were Senior Vice President Betsy West, who supervised CBS News primetime programs; 60 Minutes Wednesday Executive Producer Josh Howard; and Howard’s deputy, Senior Broadcast Producer Mary Murphy. The producer of the piece, Mary Mapes, was also fired.