The Northern Ireland Office's letters to over 200 people advising them whether they were wanted for questioning about IRA offences will be subject to "a full and rigorous examination", the judge heading the inquiry has declared.
Senior politicians, civil servants and police will be interviewed by Lady Justice Hallett about the so-called letters of assurance that were given out to 207 so-called 'on-the-runs' from 2000 onwards, in response to application by Sinn Féin.
However, she will not have power to oblige people to come before her, though a parallel House of Commons inquiry set to begin next week will have power to compel witnesses and intends to do so, if necessary.
The issue dominated debate in the House of Commons yesterday, where the Democratic Unionist Party and Sinn Féin rejected charges they had known about the arrangement, but had chosen not to acknowledge it.
The Hallett inquiry was ordered by British prime minister David Cameron after a judge ordered the abandonment of plans to prosecute Donegal man, John Downey for the murder of British Army soldiers in the 1982 Hyde Park bombing.
Saying that the prosecution could not go ahead, Mr Justice Nigel Sweeney ruled that Mr Downey had been told by the NIO - wrongly, as it turned out - that he was not wanted for questioning.
In the Commons, Independent MP Sylvia Hermon demanded proof that files into crimes committed during the Troubles remain open - even if letters were given to people who had once been suspected of involvement.
“I would hate to think that the recipients of these comfort letters had had the assurance when they received their letter that their file was closed and nobody was looking for further evidence,” she told MPs.
The Historical Enquiries Team investigating cold cases in Northern Ireland had "made inquiries about Mr Downey" but had "apparently received a negative response" from the Police Service of Northern Ireland.
“That is really worrying and troublesome,” she said.
Democratic Unionist MP Nigel Dodds said the papers lodged in court in the Downey case had made it clear that Sinn Féin's Gerry Adams had wanted "an invisible process for dealing with OTRs".
Alliance Party MP Naomi Long asked him to respond to former No. 10 Downing Street adviser Jonathan Powell’s assertion that the DUP knew of the letters but were happy for them to go ahead provided “that the blame was laid at the door of David Trimble”.
Replying, Mr Dodds declared: “I have listened to a lot of the commentary and the only allegation out there about the Democratic Unionist party is one reference in one tiny section of one book.”
References to the letters in the Eames-Bradley report do not “bear out the allegation that the scheme was known”, he said, while the charge that it was known to the Policing Board is “disproven” on an examination of the record.
Conservative MP Laurence Robertson, who chairs the Commons’ Northern Ireland Committee, urged that the Sweeney judgment should be appealed, if there was the remotest chance that it could be overturned.
Attorney general Dominic Grieve has ruled out such an appeal, and did so again yesterday, saying that the Crown Prosecution Service had advised that there was no realistic prospect of success.
However, Mr Robertson said: “If a stay cannot be appealed, it cannot be appealed, but if - as the attorney general suggests - the issue is that there is no prospect of overturning the judgment, my view as a non-lawyer is that we should consider an appeal.
“It is extraordinary that a letter, which appears to be ambiguously worded, can take on greater importance than a charge of multiple murder. I do not know whether it is unique, but it is extremely unusual.”