The Bloody Sunday inquiry is deciding what action to take next after a witness today refused to identify an alleged gunman said to have fired on troops during the disturbances.
William Harley would not confirm the identity of Tony Rush, who has been named as the gunman in previous statements, although he admitted he knew who had fired the five or six shots.
"I would not be guilty of naming the man who carried out that silly action. I just cannot do it," he said.
Mr Rush has already been named in a statement by another witness, Anthony Joseph Call.
13 unarmed civilians were shot dead by British paratroopers following a demonstration on January 30, 1972.