A former mayor of Derry has told the inquiry that he found evidence which indicated shots had been fired on Bloody Sunday from a British army observation post on top of the Embassy Ballroom.
This was the tallest building in the city centre and a location not previously implicated in the shooting.
English-born Mr Leonard Green, who served with the British navy, later worked as an engineer in Derry's telephone exchange and became an active member of the civil rights movement in 1968. He became mayor of Derry in the 1980s.
He was at work inside the exchange during the shootings, but the next morning he went into the Bogside and noticed a number of fresh bullet holes. One set of these was through a galvanised telephone cable casing on the end wall of Block 2 of Rossville flats.
The witness said that by looking through these holes he could see they were directly in line with the army post on top of the Embassy Ballroom. He said as far as he was aware there had been no consideration of the possibility that shots had been fired from this point.
He said he was convinced that this was what had happened, although Mr Edwin Glasgow QC, for soldier witnesses, put it to him that there was no evidence that any shot was fired from that position.
Ms Sinead McNicholl, who was secretary of the North Derry committee of the Northern Ireland Civil Rights Association in January 1972, described witnessing paratroopers attacking a civil-rights protest march to Magilligan internment camp on the north Derry coast a week before Bloody Sunday.
She said there were lots of people beaten - "It was just absolutely unbelievable."
In reply to Mr Arthur Harvey QC, for a number of relatives of Bloody Sunday casualties, she said she attended all the civil rights parades and had never known the IRA to use such a parade to shoot at the army.
Replying to Mr Glasgow, the witness said she did not agree with the view that NICRA was "heavily penetrated" by the Official IRA.
The inquiry continues today.