Years after Bloody Sunday Don Mullan used to bring people who came to see him in his native Derry on a tour of sites that were important to him, in an effort to impress on his visitors the extent of the tragedy that had been inflicted on his city.
In 1985 he brought this reporter first to Derry City cemetery. He told the stories of the violent deaths of many of those buried there: soldiers, IRA members, republican hunger strikers and the dead of Bloody Sunday. From the graves he pointed across the city to the Rossville Flats, where they died.
A few minutes later we were down at Rossville Flats, and he showed us where he had been that day, as a young 15-year-old on his first civil rights march. His parents had given him permission to go because it was known the IRA had agreed to stay away.
He recounted the story again yesterday, as he did that day in 1985, and has done perhaps hundreds of times.
"It was a cold, crisp day with a beautiful blue sky, the type of day you would enjoy going for a walk. There was a carnival-type atmosphere with people in a relaxed mood indulging in friendly banter."
He remembers making his way to Free Derry Corner for the rally, as a man with a megaphone urged the marchers to do. Then he saw Paras fanning out across waste ground behind him.
He remembers going back to throw stones, which he says was the ritual reaction at the time. But then he saw a Para fire a rubber bullet and another adopt the firing position.
He saw three soldiers viciously beating a man on the ground with rifle butts. He thought better of throwing stones, realising that this was no routine snatch squad.
`Then I heard the unmistakable sound of SLR rounds being fired. Michael Kelly was standing 2 1/2 feet from me. I remember him grabbing his abdomen and his cry of despair and disbelief.
"Then it seemed as though we were engulfed in gunfire."
There are six or seven minutes missing from his recollection. He has seen photographs in which he appears to have gone past Michael Kelly's body, but he has no recollection of it.
Nevertheless, in 1985 he gave an extraordinarily detailed and vivid account of what had happened, who had been killed where.
In 1985 we stood on a corner opposite Rossville Flats, at the exact spot where he had stood on January 30th, 1972. He pointed up to where he thought the wall above him had burst as he stood under it.
He now realises that a bullet had hit the wall. The hole was still there. He always thought it was very high.
He remembers being a mile away then, going up steep steps towards home. He does not remember getting there but he must have gone through Glenfada Park, where some of the most horrific killings took place.
On the steps a woman asked him what was happening. "I said, `Missus, there must be at least six people dead.' I don't know why I said six."
He left Derry after finishing school, spending two years in a seminary before leaving to study youth and community work at Ulster Polytechnic. He then did development studies at Kimmage Manor and was appointed director of AFrI. He worked in Brazil in 1982-'83 with Concern Worldwide.
He didn't know then that he wasn't finished with Bloody Sunday. In advance of the 25th anniversary he began working on Eyewitness Bloody Sunday, The Truth, which brought together eyewitness statements, recently released archival material, transcripts of army radio contacts, and reassessments of the medical and ballistic evidence.
As he read through the eyewitness statements, he noticed that about one in 10 seemed to suggest that bullets had been fired from a high point in the vicinity of the Derry Walls. He remembered the wall bursting, high above his head.
A friend, Gerry McColgan, pointed to something odd in the post-mortem examination notes on Michael McDaid. He had been killed by a bullet travelling downwards, front to back.
Further study of the postmortem notes showed five people on the day were hit by bullets with downward trajectories, and all were in the same area. Three had wounds showing identical 45degree downward trajectories.
A forensic expert he brought from the US concluded that some bullet holes remaining in the walls around the scene of the killings came from near the City Walls. Don Mullan believes the one that hit the wall above him did so too.
Speaking from Derry yesterday, Don Mullan said there was a lot of emotion in the city. "It's been a long day coming," he said, "especially for the families. It's great that's it's here."
The British decision to hold a new inquiry is a response to a dossier from the Irish Government, which relies heavily on Mullan's book.
Don Mullan brushed off personal congratulation. "Today is for the families. Yes, my book has made a contribution, as has a lot of other material.
"But the reason we are where we are now is that the families of those murdered on the day have remained faithful to the memories of the innocence of their relatives."