Face to face with a UVF gunman he knew to be personally responsible for several close-quarter sectarian killings, a detective friend of mine tried to get into the mind of the murderer.
During an interrogation of the UVF killer, the now-retired officer asked him a simple question: "How do you cope with what you have done and what you are doing?"
According to my old RUC source, the Shankill Road loyalist nonchalantly shrugged his shoulders and replied: "Just go for a few pints afterwards."
You would like to imagine that such a cold-blooded, indifferent answer was a rarity among perpetrators on all sides during the Troubles.
You would think (as many have experienced) that the ghosts of those they slaughtered haunt them down through the years.
Just picture what has gone on in the minds of the abductors and murderers of Ann Ogilby, who fell into the hands of a squad of UDA harridans in the summer of 1974.
Ann is one of those forgotten victims of the Troubles, far less famous than other women, such as Jean McConville, her end no less savage and brutal than any of the fates of the IRA's Disappeared.
With Peter Robinson and now Sammy Wilson indicating that the DUP may accept some form of "limited immunity" for those who committed Troubles-connected crimes, it is worth recalling the death of Ann Ogilby – and many others – to put this debate in some historical context.
This killing was not so much motivated by sectarianism – Ann was a Protestant – but rather jealousy. She was the target of whispering games among the UDA in south Belfast – particularly the wife of a local loyalist "commander".
After one attempt to kidnap and interrogate her in a UDA "romper room" in Sandy Row, a group of loyalist women finally sated their bloodlust.
Ann was eventually taken to a UDA-controlled drinking den at Hunter Street, in Belfast, close to the city centre, while her six-year-old daughter was held in an adjacent room in the building. The 31-year-old stood accused of succumbing to the advances of the UDA woman's husband and she and her friends subsequently battered Ann to death with a number of implements, including a brick and a club. At one point in the torture-killing, the women stopped for a smoke-break and even put make-up on, preparing for a disco later that evening. The child wailed next door as her mother died from her injuries. Later, Ann's body was taken away by UDA men and dumped at the side of the M1.
Anyone who believes in justice would hope that those behind such gruesome brutality, especially women, some of them mothers, would have lived the rest of their lives haunted by the screams of their captive, as well as her only child next door.
We may never know how many of those involved in this torture-killing – like so many other ones, where Catholic civilians were the victims – eventually came to realise the evil they had done.
How many, you wonder, ended up drunks, or Valium-addicted zombies, having been unable to cope with the enormity of their crime? How many went to early graves through stress, guilt and addiction?
Yet what are the chances – even if any of those directly involved in Ann Ogilby's murder remain alive – that the survivors would take up the offer of "limited immunity" and admit to a public forum what they did on that summer evening nearly 40 years ago?
Multiply cases similar to this dozens of times over and you start to realise the vast web out there of perpetrators, abetters and cheerleaders who goaded on and facilitated gangs like Ann Ogilby's killers. Barring a Damascene conversion, there is little in it for them – except the possibility of personal demonisation in wider society.
Ever since the police were granted leave in America to seize the Boston College tapes, there is slim chance of individual IRA members openly confessing publicly about what they did during their so-called "war". Ditto not only the loyalists, but also members of the security forces, north and south, who were engaged in the secret, underground war.
Prior to the US courts agreeing to the PSNI's demand for the Boston tapes, this writer, alongside a fellow author, had been seeking out police officers on both sides of the border with a view to creating a similar, after-death archive.
The project was going to be a parallel book and set of personal testimonies from the other side of those who had talked to Boston College.
However, once it became apparent that the US authorities were going to force Boston College to surrender the tapes, the entire project – potentially involving highly experienced ex-RUC and Garda Siochana Special Branch officers – collapsed.
We were told in no uncertain terms that no-one was willing to talk anymore, lest they face breaches of confidentiality, lose their pension, or even face prosecutions.
"Limited immunity" will, therefore, neither lessen the fear of legal, or other kinds of future, retribution, or, indeed, prompt some of the worst perpetrators of war-crimes-type killings and torture, such as Ann Ogilby's tragic end, to tell the truth.