The trial of a Limerick man on an IRA membership charge was adjourned at the Special Criminal Court yesterday after the court heard that a key garda witness was ill. The case against Mr John Costello (33), of O'Dwyer Villas, Thomond gate, had opened when the State counsel, Mr Sean Ryan SC, asked for an adjournment. Mr Costello has pleaded not guilty to being a member of the IRA on July 23rd, 1996.