Solicitors acting for the families of the 13 men shot dead in Derry on Bloody Sunday have said that new evidence gathered by independent experts proves that the forensic evidence presented to the Widgery Inquiry into the 1972 killings was worthless.
Meanwhile, Dr John Martin, the former Northern Ireland Office forensic expert who gave evidence to the Widgery Inquiry, has said he now believes that it is no longer possible to accept many of his original conclusions.
The new findings come from three English scientists commissioned by the Bloody Sunday Inquiry team, under the chairman ship of Lord Saville of Newdigate.
The scientists, Dr John Lloyd, Dr R.T. Shepherd of the St George's Hospital medical school forensic medicine unit, and Mr Kevin O'Callaghan, a senior forensic scientist with the Forensic Science Service in London, were asked to re-examine Dr Martin's forensic evidence.
Dr Martin told Lord Widgery in 1972 that many of the victims had been exposed to lead particles discharged from firearms.
However, Dr Lloyd stated in his report that Dr Martin's evidence was "worthless" and said that Dr Martin, who gave a fresh statement to the inquiry last March, now considered that his own results in relation to victim Jack Wray "do not support his original conclusion that the results were consistent with exposure to firearms discharge".
Dr Lloyd also contradicted Dr Martin by stating that there was "no evidence on which it may be supposed that any other of the deceased was associated with explosive substances".
His reports states: "The absence of control testing nullifies any evidential significance that Dr Martin's results might have had. The absence of any control samples also nullifies any possibility there might have been of obtaining any meaningful results from a re-analysis of the samples that have been retained."
Dr Lloyd also pointed out that the bodies of three of the victims - Michael McDaid, William Nash and John Young - had been transported to Altnagelvin Hospital in an armoured personnel carrier. "Such a vehicle is likely to have been heavily and continuously contaminated with firearms residue", Dr Lloyd said. "The results on McDaid [on whom Dr Martin found lead particles] are explicable solely on this basis. Apparently McDaid's bro ther was a plumber. McDaid might, therefore, have been regularly exposed to lead particles. In my view, as evidence of the event, the results are worthless."
Meanwhile, in his statement to the Saville Inquiry last March, Dr Martin, who has retired, said that he now questioned his 1972 interpretation of positive test results. "At the time of Bloody Sunday, the risks of contamination from environmental exposure to lead were not well understood. This was a very unknown area. For example, the nature and distribution of particular lead contamination from employment activities and things such as petrol emissions had not been researched or closely considered.
"With the benefit of hindsight and having reviewed all the department of industrial and forensic science case files, I do not believe it is still possible to say that there is a `strong suspicion' that a positive lead test may have resulted from exposure to discharge gases from firearms. I could only now say that such a positive test may give rise to `a suspicion'. "