A witness told the inquiry yesterday he saw an Official IRA man, whom he knew only by the nickname "Friar Tuck", jump out of a car which arrived in the Bogside after the shooting by the soldiers had ended.
Mr Bernard Doherty said that this man had a rifle. He said: "I remember commenting (to him) `You're a bit late', meaning he was a bit late to take action or get revenge. Other people were saying the same."
Earlier, another witness, Mr Patrick Doherty, told Lord Anthony Gifford QC, for a number of victims' families, that he was 16 years old at the time of Bloody Sunday and had taken part regularly in rioting.
Asked by Lord Gifford why he did so, the witness said that his parents had never brought him up to behave like that, "but we were harassed on a daily basis".
Going to work past army posts, soldiers "used to pelt us with battery cells every morning, and when we went into town they used to search us and frisk us . . . they used to hit us up between the legs and all".
"So the only way you could get your own back was to go out and stone them," he said. Another witness, Mr Christy Lavery, who was aged 37 on Bloody Sunday, described seeing a soldier beating an elderly man with a rifle butt. He said: "I ran over to the soldier and grabbed the gas mask he was wearing in an attempt to pull it off his face so that I could hit him. He put both his hands up to try to secure his mask and dropped his rifle.
"I placed a foot on his chest and pulled at his gas mask but did not succeed in getting it off. Within seconds I saw another soldier coming towards me and I ran off."
The inquiry will resume on Monday.