PETER Keeley, better known by the name Kevin Fulton, was recruited by British military intelligence to spy on the IRA in the mid-1980s.
Originally from Newry, he had joined the British army when he was 18 before being selected to spy on republicans in the Down and Armagh areas.
He returned to civilian life after being given false discharge papers so he could begin infiltrating the Provisional IRA.
He allegedly became one of the organisation's bomb specialists and was at the heart of many operations, while also passing information back to his handlers.
But when the RUC foiled an attempt by the IRA to kill senior RUC detective Derek Martindale in 1994, Keeley was outed.
He claims he was abducted, tortured and interrogated by Freddie Scappaticci, the west Belfast man who denies allegations that he was another army spy codenamed Stakeknife.
It later emerged that he had tipped off police about the attack.
Keeley has also claimed he warned his police handlers in August 1998 that the real IRA was planning an attack, shortly before 29 people including a woman pregnant with twins were killed in Omagh.
More recently he has given evidence to the Smithwick Tribunal, alleging Garda collusion in the IRA murders of RUC Chief Supt Harry Breen and Supt Bob Buchanan after leaving Dundalk Garda Station in 1989.
He rejected claims he was a "pathological liar" and described his role as an agent as a "labour of love", saying he had worked for the British army, MI5, Customs and excise and police.
Suzanne McGonagle