Two members of a six-strong scientific committee set up by Sir John May as part of his inquiry into the affair believe that contamination at the government laboratory where the hand swabs were tested was the most probable explanation for the pattern of results purporting to show traces of explosives on the family's hands.
But - dashing the family's hopes that the matter would finally be resolved - this was dismissed by others as no more than 'one of many hypothetical contamination possibilities'.
David Clarke, QC to the inquiry, said that the division in scientific opinion may mean Sir John will be unable to conclude whether the swabs had been contaminated. He told the inquiry: 'You may feel that you can do no more than to receive and take note of the opposing views.'
But Mr Clarke emphasised that Sir John's interim findings in July 1990 and indeed the conclusion of the Court of Appeal which quashed the convictions last year - that innocent contamination could not ruled out - remained unchanged by the scientific committee's findings.
Referring to Sir John's criticism of scientists at the Royal Armament Research and Development Establishment, who carried out the tests, and prosecutors and judges involved in the case, Mr Clarke said: 'Nothing in the work of the scientific committee affects the other grounds on which you based the recommendation in your interim report - namely your conclusions concerning the accuracy and the reliability of the scientific witnesses and some aspects of the conduct of the trial.'
Annie Maguire, one of those freed, said: 'I'm not surprised that they are still casting doubt. They can cast doubt and cast doubt, but we know the truth and we can live with that.'
A section of the report said that new, sophisticated tests on the old swabs tended to confirm that there were traces of nitroglycerine; it had been suggested that dyestuffs could have produced the same results. But the scientists said they could not conclude that the minuscule amounts of nitroglycerine detected related to events in 1974. One reason was that, during the 17 years in storage, they could have been contaminated.
The Maguire Seven, as they became known, were convicted in 1976 of possessing explosives on the basis of the forensic tests which, the prosecution claimed, showed they had been kneading quantities of nitroglycerine. They had completed sentences of between 4 and 14 years before their convictions were quashed. One, Guiseppe Conlon, died in prison.
The division on the committee was underlined by the fact that Dr John Lloyd and Dr Brian Caddy, the two scientists on it instructed by the family and by those representing Mr Conlon, produced their own report giving their explanation for the results - which showed a declining number of positive results as each person's hands were tested.
They claimed ether used in the testing process was contaminated, and carried out tests that mimicked the results obtained against the Maguires.
Scientists on the committee instructed by the Royal Armament Research and Development Establishment brought out an opposing report dismissing the LLoyd / Caddy conclusions as hypothetical and relying upon too many assumptions.
But Alistair Logan, solicitor for the family, accused the scientific committee of 'ducking the issue'. He said: 'While concerned that nothing explained the unique and curious pattern in the Maguire results and confirming that the Crown case at trial not be correct, the committee failed to investigate experimentally possible sources of contamination.
'It thus forced us to carry out those tests and we as a result have now been able to provide the probable explanation, namely contamination of the laboratory ether. The committeee could only offer opinions on possible contamination,' he said.
The hearing was adjourned until Thursday when all the parties involved will make submissions on the committee's findings.
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