Sean O'Callaghan

'''Sean O'Callaghan''' (10 October 1954 – 23 August 2017) was a member of the Provisional Irish Republican Army (IRA), who from the late 1970s to the mid-1980s worked against the organisation from within as a mole for the Irish Government with the Garda Síochána's Special Branch.

In the mid-1980s he left the IRA and subsequently voluntarily surrendered to British prosecution for actions he had engaged in as an IRA gunman in the 1970s. Following his release from imprisonment, he published a memoir detailing his life in Irish Republican paramilitarism entitled ''The Informer: The True Life Story of One Man's War on Terrorism'' (1998).

Former Irish Prime Minister Garret FitzGerald described O'Callaghan as one of the Irish Government's most important spies operating within the Provisional IRA during the late 20th century's The Troubles. Provided by Wikipedia