Secret documentation unearthed by the new Bloody Sunday inquiry team suggests that there was strong pressure at the highest British army command level in Northern Ireland to relax rules restraining soldiers from firing on unarmed rioters.
Top-ranking British officers will be subjected to intense cross-examination about a memo which indicates that Maj Gen Robert Ford, then in day-to-day command of the army in the North, favoured allowing soldiers to shoot "selected ringleaders" among the rioters in Derry's Bogside in 1972.
The irony is that, even as the new tribunal of inquiry headed by Lord Saville of Newdigate prepares to open formal hearings in a fortnight, there is a growing mood of cynicism in Derry about its likely effectiveness in discovering the truth.
Relatives of the victims shot by paratroopers after a civil rights march in the city on January 30th, 1972, are incensed and disillusioned as their legal teams encounter persistent difficulties in securing access to all the statements and material gathered in advance from British army and Ministry of Defence sources.
The relatives of the dead and wounded were already outraged at the failure of the Saville inquiry to ensure that soldiers who give evidence will be named. Their mood of scepticism has hardened since revelations that several rifles used by the paratroopers, which could have yielded crucial forensic evidence, were destroyed as recently as January, despite an undertaking by the Ministry of Defence that they would be preserved.
However, the wide-ranging powers ceded to the tribunal have enabled the discovery of previously classified material on policy discussions at high military and political level at the time.
Among this material is Gen Ford's memo to his immediate superior, Lieut Gen Harry Tuzo, about tougher measures that should be adopted to put down disturbances in the Bogside.
Revealed in a forthcoming book on Bloody Sunday by two journalists, Peter Pringle and Philip Jacobsen, the memo records Gen Ford's recommendation that "the minimum force required to restore law and order is to shoot selected ringleaders . . . after clear warnings have been given."
It remains to be established, through cross-examination of scores of officers and soldiers, whether the use of the combat-ready and highly aggressive paratroops on the day represented a deliberate intention to try out this policy recommendation.
The inquiry must also investigate a further element of Gen Ford's proposed plan, that he intended to issue modified rifles with smaller-calibre ammunition to the troops so that "collateral damage" to other civilians might be minimised when rioters were shot.
Material has emerged which suggests that up to 30 of these modified weapons had been sent to Derry for training purposes. Suspicion has arisen that some might have been issued and used on Bloody Sunday, and in this regard new questions have been raised about the recent "unauthorised" destruction of rifles.
Intensive preparations are in train to upgrade facilities at Derry's Guildhall for the hearings, which could last up to two years. Live video links are being put in place so the proceedings can be viewed on screens in the nearby Rialto entertainment complex, in case there is insufficient space in the Guildhall for the public.
The primary concern of the victims' relatives is to have the inquiry establish finally and definitively that those who were shot were unarmed and innocent. Lawyers for the British army and the Ministry of Defence will seek to persuade the tribunal that the soldiers only opened fire, and were justified in doing so, after they were fired upon from the Bogside.
A mass of detailed statements, from civilians and soldiers, has already been gathered by the inquiry's solicitors. The tribunal's preparatory research work, and legal proceedings associated with it, have already cost an estimated £13 million.
However, beyond the fine detail of who shot whom and in what circumstances, the higher policy issues in the background to Bloody Sunday carry huge political implications. A number of very senior British and Northern Ireland political figures have yet to respond to the tribunal's request to supply statements to it.
The declassified material now gradually being uncovered by the inquiry's preliminary operations points to influences and strategies at work which were only surmised, but could not be corroborated, immediately after the shootings.