Solicitors representing two men jailed for the murder of the first member of the PSNI to be shot dead in Northern Ireland, say the convictions should now be deemed unsafe.
It comes as information has emerged claiming MI5 agent Dennis McFadden infiltrated a campaign group, during a failed appeal launched by John Paul Wootton and Brendan McConville.
The two men were convicted of the murder of Constable Stephen Carroll, shot dead as he responded to a 999 call in Craigavon, Co Armagh, in 2009.
McFadden went missing in August, around two weeks before the arrest of nine members of the dissident political group Saoradh and Palestinian doctor Issam Bassalat (62) of Telford Road, Edinburgh.
He is believed to be in protective custody and will act as a key witness against the accused, alleged to be the leadership of the New IRA.
A Channel 4 report, aired this week, examined the role of the MI5 agent in the infiltration of the Brendan McConville defence and justice campaign led by the late Gerry Conlon.
One of the Guildford Four, Conlon who died in 2014 had spent 15 years in prison after being wrongly convicted of an IRA bombing campaign, he had met with McFadden on several occasions.
The long standing MI5 agent was a close friend of veteran IRA man Tony TC Catney, who also played a key role in the justice campaign.
Catney, who died of cancer in 2014, attended many of the appeal hearings, and was present in court with McFadden when Lord Chief Justice Sir Declan Morgan said he and his fellow appeal judges were satisfied that the original verdict had been correct.
The family of Brendan McConville claim Dennis McFadden infiltrated their campaign and sat in on meetings linked to the appeal of the conviction, giving him access to sensitive material.
He is also listed on Companies House as a secretary of Justice Watch Ireland, a since dissolved campaign group registered to an address at a community forum in west Belfast.
The organisation actively campaigned for the two men, with McFadden handling much of the group's social media presence.
The Irish News understands that McFadden also befriended a close relative of John Paul Wootton, who was just 17 at the time of the murder, and was regularly seen in his company in the Ardoyne area of north Belfast.
Speaking on the phone from Maghaberry Prison, Brendan McConville told Channel 4 News: “I believe he sabotaged my appeal. I felt that he had a real genuine concern on justice. Little did I know that it was the hand of MI5.”
The McConville family also claim the MI5 man took control of their social media campaign and refused to give them the passwords.
As a result of this information Darragh Mackin and Peter Corrigan of Phoenix Law, who act on behalf of the two men convicted of the murder of Constable Carroll, say they are to submit an application to the Criminal Case Review Commission for consideration.