An inquiry into IRA-Garda collusion in the murders of two of the most senior RUC officers to die in the Troubles should be reopened on the back of the Garda surveillance scandal, a lawyer for one of the dead men's families has said.
Revelations that phone calls at stations have been recorded since the 1980s could have major ramifications for investigations into the Provo ambush of Chief Superintendent Harry Breen and Superintendent Bob Buchanan on their way home from a security meeting in Dundalk in March 1989.
There may also be implications for six other cases where collusion has been suspected, lawyer for the Breen family John McBurney said.
Judge Peter Smithwick found gardai colluded in the RUC men's double murder but failed to pinpoint definitive evidence to blame an individual officer for informing the IRA of their movements.
His long-running inquiry was repeatedly told by senior gardai that they did not have suspicions of an IRA mole among their ranks in Dundalk Garda station.
Mr McBurney said it would be incredible if there were no tapes of calls in and out of Dundalk when lines at the divisional headquarters of Drogheda and Monaghan were understood to be under surveillance.
He said: "Judge Smithwick must be troubled. He has the power to reopen an inquiry if he feels that he had information deliberately withheld and that could have been an attempt to pervert the course of justice.
"He would want to look at that further."
Other high-profile cases which may have been discussed on recorded calls in the border region include the murder of Lord Justice Maurice Gibson and his wife Cecily in an IRA bomb at Killeen, Newry, Co Down, 1987 after they had crossed the border; Cooley farmer Tom Oliver, who was murdered by Provos in 1991 for allegedly being an informer; and the murder of electrical contractor Terence McKeever, who worked in RUC stations and was tortured and killed by the IRA in June 1986 in south Armagh.
Two other cases are the deaths of four RUC officers - William Wilson, 28, Stephen Rodgers, 19, David Baird, 22, and Tracy Doak, 21, in the bombing of a Brink's-Mat van in 1985 moments after the RUC had taken over escort duty from gardai and the killing of businessman John "Big Note" McAnulty who was abducted by the IRA from a border pub in July 1989.
There was also the mistaken identity murder of Robert and Maureen Hanna and their seven-year-old son David in a bomb at Killeen, Newry after holidaying in Disneyland in July 1988. The IRA said it meant to kill Judge Eoin Higgins.
Mr McBurney said he was not claiming a tape exists from Drogheda or Monaghan that proves calls were made to the Provos with information that led to those killings but that they may contradict evidence from gardai who told the tribunal there were no concerns about an IRA mole.
He said: "It beggars belief that the judge was trying at a basic level to get details of phone calls in Dundalk and could not, yet there could be wholesale recording of conversations at that station and other stations.
"The very first thought that came into my head was the days and days of evidence that we listened to from engineers and garda specialist officers convincing us that the Provos had not bugged Dundalk, that everything had been checked thoroughly, and all along the Garda had bugged themselves."
Ernie Waterworth, solicitor for the Buchanan family, said the revelations that recordings might exist of phone calls in and out of Dundalk around the time of the double murder is frightening.
"Even the fact that Drogheda and Monaghan could have had the phone lines recorded, to me that causes concern," he said.
"The people in Dundalk would have been talking to Drogheda when making arrangements for the movements of VIPs, protective operations. The visits of (late RUC Chief Constable) Sir John Hermon, Judge Gibson... All of that is frightening what you could take from it.
"I feel that all of that, the likes of the communications from Garda HQ in Dublin to border stations and so on, Dundalk would have to have been notified.
"The revelations are concerning."
Mr McBurney said he is minded to contact the head of a commission of inquiry set up to investigate the bugging scandal with his concerns once they are appointed.