An eight-year tribunal found an IRA mole in the Garda station in Dundalk tipped off a terrorist hit squad that Chief Superintendent Harry Breen and Superintendent Bob Buchanan were attending a meeting in the town on the day they were killed in March 1989.
Former Garda detective sergeant Owen Corrigan said he did not believe Judge Peter Smithwick's ruling that one of his colleagues would have colluded in the murder of the two brave RUC officers.
"Unfortunately, Judge Smithwick's finding has now placed a cloud of suspicion over all former members of Dundalk Garda Station in circumstances where there is no direct evidence of collusion," he said.
Mr Corrigan welcomed that there was no finding of collusion on his part in the double murder.
"I do not accept, however, his findings that I had an inappropriate relationship with the Provisional IRA," he said.
All my dealings with the Provisional IRA were for the purposes of gathering information and/or intelligence to support An Garda Síochána in defending this state and its people during the Troubles.
Owen Corrigan, ex-Garda detective sergeant
It was the naming of Mr Corrigan as an IRA mole that sparked the lengthy probe.
In April 2000, DUP MP Jeffrey Donaldson stood in the Houses of Common and, under parliamentary privilege, said the detective sergeant colluded with the IRA in the 1989 murders.
The allegation was made to the MP by British double agent Peter Keeley, also known as Kevin Fulton.
But Judge Smithwick believed Mr Corrigan became disaffected, possibly in the 1980s, with the detective branch in Dundalk where he was based.
He stated that what may have started out as a professional relationship with subversives for the legitimate purpose of intelligence-gathering, ultimately developed into a relationship of "an inappropriate nature".
Mr Corrigan said the finding was based to a large extent on the acceptance of evidence given by Mr Fulton, which he disputed during public sittings.
"For 32 years I served as a member of An Garda Siochana and in the border area during a time of unprecedented troubles," he continued.
I served my force and my country to the best of my ability during a time when the campaign of violence by the Provisional IRA was at its height.
Owen Corrigan, ex-Garda detective sergeant
"I suffered considerable violence and intimidation, with 'wanted for treason' posters of me being erected by republicans in Dundalk and surrounding area.
"My wife and I were also attacked by so-called republicans while socialising in Dundalk.
"As Judge Smithwick noted, I was also severely beaten up by members of the Provisional IRA."
Mr Fulton claimed "a friend" of the IRA - who he alleged was Corrigan - tipped off the IRA that the RUC were in Dundalk on the day they were ambushed.
He also told the tribunal that Mr Corrigan helped the IRA and destroyed evidence from one of the worst atrocities in the Troubles, the 1979 Narrow Water bomb attack, which killed 18 British soldiers.
The agent, who spied on the IRA from the 1980s, claimed the detective also cleaned fingerprints from where a 1,000lb bomb was found in Omeath and once told the IRA that Co Louth farmer Tom Oliver was an informer.
Two months later, in July 1991, Mr Oliver was kidnapped and murdered.
Corrigan went on certified sick leave in December 1989 and officially retired from the force on 4 February, 1992.
He has called all of the claims a monstrous lie.
Everyone knows the IRA was responsible. That was never in question.
Gerry Adams, Sinn Féin president
On Wednesday, Sinn Féin president Gerry Adams caused outrage when he said that he does not believe Gardaí colluded in the IRA murders of two senior RUC officers.
He described the report's findings as "contradictory," saying that the officers had a laissez-faire disregard for their own security.
"The Guards, and the judge criticises this, didn't appear to be dealing with them in security that was required of men of their profile and standing," he said. "The RUC in the North, similarly, weren't paying heed to this.
"And here they are, on an unapproved road, going through republican South Armagh, at a very bitter and tense period of the conflict. So when that happens nobody needs to infiltrate anything."
Responding to criticism of his comments, which spanned the political divide, the Louth TD said: "It is nonsense to suggest that I was blaming the two RUC officers for their own deaths.
"There is also no question but that the Smithwick report records serious concerns about the security arrangements for RUC officers travelling to Dundalk through South Armagh. These include the fact that information about possible IRA attacks on RUC officers crossing the border was passed to Garda Headquarters and passed by it to the RUC."
He continued: "It is a fact that RUC Officer Bob Buchanan was crossing the border on average 10 times each month and on most occasions he travelled in his own car which was 'readily identifiable.'"