[3] After completing his schooling, Collins worked for a time in the Ministry of Defence in a clerical capacity in London before studying law at Queen's University Belfast, where he became influenced by Marxist political ideology.
[7][page needed] Collins joined the Provisional IRA during the blanket protest by Long Kesh inmates in the late 1970s, which sought Special Category Status for Irish Republican paramilitary prisoners, and he became involved in street demonstrations at this time.
His planning was directly responsible for at least five deaths, including that of Major Ivan Toombs of the Ulster Defence Regiment in January 1981, with whom Collins worked in the Customs Station at Warrenpoint, and possibly three times that number.
His belief in the martial discipline of IRA's campaign had been seriously undermined by the murder of Norman Hanna, a 28-year-old Newry man on 11 March 1982 in front of his wife and young daughter, who had been targeted because of his former service with the Ulster Defence Regiment, which he had resigned from in 1976.
[11] His uneasy state was further augmented by being arrested under anti-terrorism laws on two occasions, the second involving his detention at Gough Barracks in Armagh for a week, where he was subject to extensive sessions of interrogation in 1985 after an IRA mortar attack in Newry, which had claimed the lives of multiple police officers.
These doubts had been made worse by the strategic view that he had come to that the organisation's senior leadership had in the early 1980s quietly decided that the war had failed, and was now slowly manoeuvering the movement away from a military campaign to allow its political wing Sinn Féin to pursue its purposes by another means in what would become the Northern Ireland peace process.
[12] On release from prison he spent several weeks being counter-interrogated by the IRA's Internal Security Unit to discover what had been revealed to the authorities, after which he was exiled by the organisation from the northern part of Ireland, being warned that if he was found north of Drogheda after a certain date he would be summarily executed by it.
[15][16] The technical acquittal in the Crown court based upon judicial legal principles made an impact upon Collins' view of the British state, markedly contrasting with what he had witnessed in the IRA's Internal Security Unit, and reinforced his disillusionment with Irish Republican paramilitarism.
Having returned to live in Newry, rather than maintaining a low profile Collins decided to take a prominent role in the ongoing transition of Northern Ireland's society, using his personal history as a platform in the media to analyze the adverse effects of terrorism.
At the same time in the media he called for the re-introduction of internment after the Omagh bombing for those continuing to engage in such acts;[18] published newspaper articles openly denouncing and ridiculing the Real IRA's campaign, alongside publicly analyzing his own past role in such activity, and the damage that it had caused on a personal and social level to the two communities of Northern Ireland.
Since his return to Newry in 1995 his home there had been intermittently attacked with acts of petty vandalism, but after the Murphy trial these intensified in regularity and severity, and another house belonging to his family in Camlough, in which no one was resident, was destroyed by arson.
[21] Collins was beaten and stabbed to death in his 45th year by an unidentified assailant(s) early in the morning of 27 January 1999, whilst walking his dogs near the Barcroft Park Estate in Newry along a quiet stretch of country lane at Doran's Hill, just within sight of Sliabh gCuircin (Camlough Mountain).
[24] After a traditional Irish wake, with a closed coffin necessitated due to the damage to his face,[25] and a funeral service at St. Catherine's Dominican Church in Newry, Collins' body was buried at the town's Monkshill Cemetery, not far from the grave of Albert White, a Catholic former RUC inspector, whose assassination he helped to organise in 1982.
[29] In January 2019, the PSNI released a statement regarding the murder that one of the assailants of Collins had been seriously injured by an accidentally sustained knife wound during the attack, and had left traces of his own blood at the scene, and that recent scientific advances in DNA evidence had increased the possibility of his identification.