 In exchange for the shortening of his sentence, McGrady was persuaded by the police to become an informer and provide names of fellow IRA members.The supergrass trial in which McGrady was the star witness, was the third such trial in Northern Ireland.It began on 5 May 1983 with ten defendants and 45 indictments including a conspiracy to murder the former Chief Constable of the RUC, Sir James Flanagan.