Mr Don Mullan, the prominent Bloody Sunday campaigner, gave evidence yesterday of his experiences as a 15-year-old schoolboy during the shootings and described how a youth was shot beside him in Rossville Street.
At the end of his evidence, Mr Mullan, author of the book Eyewitness Bloody Sunday, was challenged sharply by the tribunal chairman, Lord Saville, over a correction he had made to his original statement to the present inquiry.
Mr Mullan had pointed out that a reference in his statement to having recognised a friend of his at an IRA checkpoint concerned a period after Bloody Sunday, and not before it, as the context seemed to indicate.
The chairman remarked that the context in the statement was clearly set in the position before Bloody Sunday, and he asked Mr Mullan when it had come to his notice that this was inaccurate.
The witness said it was as he was travelling up on the train the previous day.
Lord Saville - "Mr Mullan, has anyone suggested to you that those last sentences should be put after rather than before Bloody Sunday?"
As the witness began to reply, the chairman interjected: "What is the answer to my question?"
Mr Mullan replied: "The answer is no", and when Lord Saville further asked: "You are quite sure about that?", he said: "Absolutely, yes".
Mr Mullan, whose 1997 book was instrumental in the successful campaign for a new Bloody Sunday inquiry, described earlier how he was behind the rubble barricade in Rossville Street when he saw army vehicles drive into the street at high speed.
Soldiers got out and he saw three of them using their rifle butts to beat a young man.
He then heard at least one high-velocity rifle shot and a young man standing very close to him cried out and grabbed his abdomen.
"I immediately knew that the man had been shot and my own immediate reaction was one of disbelief," said Mr Mullan. "I now know the man to be Michael Kelly."
There was then "a huge amount of gunfire" aimed at the barricade.
He was certain that he had seen no one at the barricade firing weapons or throwing bombs.
Mr Mullan described how he ran from the scene in a state of shock, and how there was "a sense of national tragedy" as huge crowds gathered for the funerals.
He said he was very clear that on Bloody Sunday innocent civilians had been cold-bloodedly shot down, and that he had no doubt that it was a catalyst for the situation becoming very serious in the months and years afterwards.
"Questions have to be asked as to why a peace-loving community to which I belonged in the Creggan and Bogside could produce young men and women who became very dedicated members of paramilitary organisations," he commented.
"It was not because we were a violent people by nature; it was not because we had a genetic defect that made us prone to violence. I think ultimately we have to look at the root causes of why this conflict happened."
The inquiry continues today.