The counsel to the tribunal yesterday completed his extensive summary of civilian evidence in relation to the deaths and injuries at the barricade.
Mr Christopher Clarke said he had dealt with portions of the evidence of some 60 witnesses, and there were very sizeable discrepancies between some of these accounts. But there were also some points on which there seemed to be a degree of consensus.
He then addressed the issue as to whether any of the victims had been shot by units other than the Parachute Regiment members in Rossville Street. He said there was a fairly widely held opinion that three of the barricade victims, Young, Nash and McKinney, had been shot by soldiers positioned on the city walls.
Part of the basis for this was that these victims had been killed by bullets entering their bodies at an angle of about 45 degrees, and it was inferred that, if standing up at the time, they must have been shot from above.
However, Mr Clarke said that the forensic team of Mr Dick Shepherd and Mr Kevin O'Callaghan had concluded that nothing in the pathology of the wounds lent greater weight to this theory than to the proposition that the victims were shot by soldiers in Rossville Street.
If shot from the walls, the deceased would have had to be bending forward at an angle of 40 degrees, to align the shot with a walls trajectory; if shot from ground level, they would have to have been bending forward at a 45-degree angle to align the track through the body with a horizontal trajectory.
There was therefore a difference in angle of shot of only five degrees, which was well within the possible error of measurement.
The consultants concluded that, in their opinion, the shots which killed Nash, Young and McDaid could have been fired from either the street or from the city walls.
However, it was clear from the injuries that all three men were facing in the general direction from where the shots came.
Witness testimony, and not pathology or ballistics, was therefore the key to resolving this matter.
Mr Clarke referred to a Channel 4 television programme which quoted an unnamed soldier, or former soldier, who said he had been on Derry's walls and that a sniper attached to his unit had opened fire. This man said that the sniper had yelled: "Bloody hell, I've got two with three shots."
Counsel said that this information was "tantalising in many respects, not least that we do not know the identity of the witness". He said that Channel 4 had declined to reveal the identity of the witness, "and the tribunal may have to consider in due course requiring them to do so".
The inquiry also heard part of a statement from a private in the Royal Anglians regiment, who said that he was stationed on the city walls and someone in his section fired his SLR.
The statement said: "I do not know whether it was an aimed shot or not. Sometimes when there was firing people would just fire themselves. I think they just got carried away. I do, however, remember the sergeant calling to `hold fire'.
"I think that there was a danger that the Paras would have been in the area of the shot. There is a danger that in those circumstances that they might have thought that they were being fired on. The shot was fired after the firing had started and after I saw the Paras moving up Rossville Street.
"Mistakes can happen. There was an occasion when soldiers in the Diamond area mistook a soldier on the walls for a gunman on the roof of the Rossville flats. They fired at the `gunman' who returned the fire."
Mr Clarke also yesterday issued an appeal for public assistance in locating a series of missing photographs which may hold vital clues to the sequence of deaths on Bloody Sunday.
He asked for help in tracing a man named John Lloyd, referred to as a journalist for the London magazine Time Out, who is said to have been given the negatives and photographs at some point after Bloody Sunday.
A witness named Thomas Eamon Melaugh has told the inquiry's solicitors that he saw the bodies of several victims at the barricade in Rossville Street and took photographs with his 35mm camera.
In his statement he said: "By this time the shooting had stopped so I went to the rubble barricade and took about 10 to 12 photographs. All were given to John Lloyd and none were returned . . ."
He continued: "I remember that Michael McDaid was in one of them and that this clearly showed that he was alive when the shooting had ended because he was standing in the middle of the rubble barricade and he was clearly not injured."