Question:  Seán Mackin had been a member of the Irish National Liberation Army, an Irish republican socialist paramilitary group formed during what year?
Sentence (from "Irish National Liberation Army"): The Irish National Liberation Army (INLA, Irish: "Arm Saoirse Náisiúnta na hÉireann" ) is an Irish republican socialist paramilitary group formed in December 1974, during "the Troubles".
Relevant evidence: Yes