Eamon Collins was dark and troubled. Maybe 15 people, possibly more, were murdered because of his actions. He betrayed his former IRA comrades. Yet he chose to live among those he betrayed and the relatives of those he was responsible for murdering.
Death threats were issued against him, his home was torched, his car was burned, he had been injured in a previous hit-and-run incident; all of which he blamed on republicans. Graffiti in the working-class estate in Newry where he lived with his wife and four children proclaimed him an informer, a tout, the ultimate insult and often the precursor to death.
But he didn't particularly care. He was possessed of a compulsive but sincere commitment to truth, and an almost aggressive fatalism that seemed to say: come and get me if you want. Yesterday, it seems, they came and got him, although it is still for the police to determine whether it was foul play or an accident.
The parallel with a similar incident in April 1997 when Collins was injured in a hit-and-run accident near his home would tend to lean towards this not being an accident. If that is the case it will take some time to determine whether this was a maverick action or murder sanctioned at a higher level.
Collins probably reckoned it would end something like this. Like some of the tormented characters in Graham Greene's novels, he lived life on the edge, taking gambles he knew could end in murder, but he was generally past worrying.
Like his fellow IRA informers, Sean O'Callaghan or Martin McGartland, he could have lived relatively safely in Britain and still made his political points. Collins, aged 45, was always more interesting than McGartland or O'Callaghan because he was more self-searching.
Having had dealings with him several times in recent years I can only surmise that his decision to go to live in Newry, despite a 1985 IRA death threat against him still in existence, was a masochistic way of confronting his past.
He admitted he was a mess of contradictions, at the same time both confronting and recoiling from what he had done. He wanted to do the impossible: be fair and contrite at the same time to his victims and his former IRA friends.
"I am trying to be sensitive and apologetic to my victims, and to the people who have suffered because of my betrayal," he said. His remorse was ambiguous. Push him so far and you'd detect residual justification for his actions. "There's no way that I can psychologically dump what I was and say, `That's an end to it'. But there is no ambiguity in my commitment to peace now," he added.
"I am not a converted terrorist. I am someone who has to work with this all the time."
Collins wrote one of the most powerful, if not the most powerful, books of the Troubles, Killing Rage. It was also one of the most honest and disturbing books of the period. It debunked the notion of romantic republican paramilitarism. As Collins himself said, it dealt with the "horrific banality" of murder.
He was intelligence officer for the IRA in the first half of the 1980s in the Newry-Warrenpoint area. Several people, possibly more than 15, died as a result of his actions. He describes in stark relief how he set up victims for assassination, how he trailed them, studied the movements of their wives and children, how he planned the actual murders, and how he organised the killers' escapes.
He didn't pull the triggers but, as he admitted, he may as well have done. In the book we see the gradual dehumanising of his personality. For instance, he describes how for two years he worked with fellow customs officer Ivan Toombs, a part-time UDR major, and how over nearly every day of that period while being outwardly friendly to him, meeting his wife and children, he coldly planned his murder.
Others gunned down Mr Toombs, but it was equally Collins's crime. On another occasion he tells of a child crying "Daddy, daddy" as her father is gunned down by the IRA. Or of an elderly off-duty policeman having a drink in a bar and seeing his killers approach: "Ah, no, boys, not me."
Or of a blindfolded informer suspect thinking he has got the all-clear but unknowingly getting the thumbs-down execution sign at an IRA kangaroo court. It goes on relentlessly. It's hard reading. Collins doesn't spare the reader or himself and he does de-romanticise paramilitarism.
He was intelligent, a small man with a large ego and interesting to chat to. Originally a very hardline IRA member, he criticised Gerry Adams in the past, and was severely reprimanded in turn by some of Mr Adams's juniors. In the end, though, he fully supported the current Adams-McGuinness strategy.
He had high regard for some IRA members, but despised others who he felt were sadistic and psychopathic. While he regretted the murder and grief he caused, he could still say about his erstwhile colleagues: "I betrayed them and I was wrong." That mess of contradictions again.
Still, he had no difficulty in giving evidence on behalf of the Sun- day Times against the Co Louth farmer, Thomas "Slab" Murphy, claiming Murphy was a senior IRA officer.
In 1985 he cracked under RUC interrogation and turned super-grass. Twelve people faced serious charges on his evidence. Eventually he recanted, and most of those were released. Some who had signed confessions were jailed.
Collins was charged with five murders, but the irony was that, though guilty, he was set free because the judge believed his confessions were induced as "a result of inhuman and degrading treatment". Collins said: "I beat the rap."
He supported the Belfast Agreement and desperately wanted it to work, but with dread he could foresee an Ireland of the future where the killers of today would be the heroes of tomorrow. That was one of the reasons he risked his life to make his point, and yesterday paid the final penalty.
Collins said: "If peace prevails, in maybe 10 or 15 years from now, people who carried out the most horrendous, merciless acts will have dirges written about them. History will be sanitised and they will be heroes, but I don't want any part of that. There was nothing heroic about this war."