Video footage was used yesterday to provide an endorsement of eyewitness evidence which had been strongly challenged by counsel representing British soldiers.
Mrs Roisin Stewart had told the inquiry that while she and others were huddled in a stairwell of Rossville Flats she heard a man with a well-spoken English accent shout through a loudhailer or megaphone down below: "If any of those bastards up there move, shoot them."
She said that on the television news that evening she heard an army officer's voice shout out: "Do not fire until you have identified a positive target." She immediately identified this voice as the one she had heard through the loudhailer.
Also on the television news she heard Col Derek Wilford, OC of the 1st Battalion of the Parachute Regiment, interviewed, and his voice was similar to the voice she had heard through the loudhailer.
Mr Edmund Lawson QC, for the soldiers, asked if she was positive about this. She replied that she was.
Counsel invited her to consider that she might be wrong. He suggested that there was no megaphone in use by army officers in that area.
Later, on the suggestion of Mr Christopher Clarke QC, counsel to the tribunal, a video relating to Bloody Sunday was played and all parties agreed that a soldier could be seen holding a white megaphone in the vicinity of the flats.
Mr Lawson said he acknowledged that "the film shows what it does". He said in his questioning of the witness: "I was reflecting what I understood our instructions to be."
Mr John Nash, whose brother, Willie, aged 19, was shot dead at the rubble barricade in Rossville Street, where his late father, Alex, was also shot and wounded, gave evidence of seeing soldiers firing shots as they got out of armoured vehicles.
He told how the family had attended his wedding on the day before Bloody Sunday. They set off together, with friends, on the march from the Creggan. He met his father at the corner of Chamberlain Street and continued towards the flats. When the heavy shooting ended he returned to the Creggan, where a friend told him Willie had been shot dead and his father had been wounded.
The inquiry resumes on Monday.