A Panorama investigation. Last August's shooting of a young Catholic, Loughlin Maginn , was the 2,744th murder since the present Northern Ireland troubles began. But it will be remembered as the killing which triggered off a damaging row between the governments of London and Dublin. Maginn was targeted and murdered by Protestant terrorists using an intelligence file leaked from within forces there to prevent such violence. Next month a report on the collusion between Loyalist paramilitaries and dissidents in the army and police will be delivered by a team of English detectives sent to plug the leaks. John Ware reveals disturbing new evidence that the principal source of leaks is from within the locally recruited Ulster Defence Regiment.