Another eyewitness was put under pressure yesterday to name people he knew or thought, even from hearsay, to have been members of the Provisional or official IRA at the time of Bloody Sunday.
Mr Charles McDaid, whose extensive evidence broke new ground on some aspects of the killings, said he was not prepared to name people.
"That would not be right for me, as it was hearsay to me who they may have been and what they were in. (These) were secret organisations . . ."
He also commented that some people would have "spoofed" about people who were "known" to have been IRA members. It did not necessarily follow that they were right, so it was hearsay.
In his statement to the inquiry, Mr McDaid had said he did not see "any known `Stickies' - official IRA members - or IRA Provisionals in the crowd" on Bloody Sunday.
Cross-examined by Mr Christopher Clarke QC, he admitted that around that time about a dozen IRA Provisionals and about four or five "Stickies" were known to him.
Asked if he was prepared to tell the tribunal who these were, he replied "no". He said he preferred not to: he had not seen them on the march, so he did not see why he should give names.
The chairman, Lord Saville, put it to him that the tribunal was trying to discover the whole truth about Bloody Sunday, and the families of the dead and wounded also wanted this. He said the tribunal wished to talk to these people to see whether they could help in regard to what happened.
He asked if the witness would be prepared to consider giving the names to the tribunal itself, not in public.
Lord Saville said: "If you told the tribunal, in the first instance in confidence, who you believed or were told were members of either branch of the IRA, then the tribunal and its staff would obviously make some inquiries of those people.
"It would then be a matter for (them), if they had anything to do with Bloody Sunday, to decide whether or not they wanted to remain anonymous.
"If they wanted to remain anonymous, they would have to apply to the tribunal and explain why . . .and the tribunal would then decide whether on not that application would succeed."
The witness asked for time to consider the tribunal's request, and the chairman said the tribunal staff would write him a letter explaining precisely what they would like him to do.
In cross-examination later by Mr Gerard Elias QC, for a number of military witnesses, Mr McDaid agreed he would not regard it as satisfactory if the British government was deciding which witnesses came forward or which did not.
He also would not regard it as satisfactory if there were elements of the IRA deciding which witnesses "from their former ranks" came forward or did not.
Earlier, the inquiry heard a graphic account of the events on Bloody Sunday from Mr Liam Carlin, who had travelled from Co Donegal with his three brothers to take part in the civil rights march.
He witnessed some stonethrowing in William Street, and then saw that the "paras" were there. "You did not throw stones at those guys, it was as simple as that. I had a sense of real fear." Shortly afterwards a youth was shot.
Mr Carlin described how he and his brothers, leaving the Bogside in their car, were dragged out and thrown against railings by paratroopers. "It was terrifying. We were rifle-butted and rifles were placed at our chins . . .We thought someone was going to be killed. I have never seen worse wide-eyed hatred before.
"Nobody can hate that much, there must have been an element of fear in there too. The soldiers kept looking round for help from each other. If one moved, the others moved with him. (They) were completely hyper; they were venomous."
The inquiry continues today.