A retired forensic scientist fears his life may be endangered if he has to give evidence in public at the hearings in Derry's Guildhall, the inquiry heard yesterday.
Dr John Martin, who took paraffin swabs to detect lead particles on the bodies of Bloody Sunday victims in 1972, sought an order from the tribunal enabling him to be screened from the view of the public, the media and the victims' families while giving evidence next month.
Mr Stephen Ritchie QC, counsel for Dr Martin, said his client's evidence would relate to the presence or otherwise of firearms discharge on clothing. It was highly contentious in the context of the inquiry.
Counsel said that, unlike the soldier witnesses, his client's name would be known.
He would also continue to live in Northern Ireland after he had given evidence.
A Special Branch intelligence assessment had concluded that he was "at a moderate risk of threat, with potential to increase".
He asserted that he had "a reasonable and genuine fear for his personal safety", counsel said.
Mr Seamus Treacy QC, for a number of families of the victims, opposed the application.
He pointed out that Dr Martin had given evidence in public and unscreened before the Widgery tribunal in 1972.
Counsel said that he did not know of any case throughout the history of the Northern Troubles of any forensic scientist ever seeking screening, even in the many major terrorist and other trials which took place.
The chairman, Lord Saville, said the tribunal would give a ruling on the matter as soon as possible after considering all the submissions made.
The inquiry will resume on Monday.
The deletion of a line from yesterday's report on the inquiry resulted in a misleading version of comments by Lord Saville.
A sentence in the second-last paragraph of the report should have read: "It did not seem to the tribunal that full representation was required in the interests of justice and fairness, but the matter would be reviewed if circumstances changed, Lord Saville said."