A senior garda intelligence officer has confirmed to the Smithwick Tribunal that they received information that there was "improper contact" between a then serving detective sergeant in Dundalk and a person linked to the IRA.
Det Chief Supt Peter Kirwan said: "In at least one or two cases that information was counterbalanced by information emanating from [Owen] Corrigan indicating that the relationship was properly motivated and that some intelligence dividend was accruing from that relationship."
Mr Corrigan is one of three former gardaí being investigated by the Tribunal to see if they passed on information to the IRA, which led to the murder of two senior RUC officers minutes after leaving a meeting in Dundalk Garda Station in March 1989.
Mr Corrigan, former Sergeants Leo Colton and Finbarr Hickey all deny the allegations.
Mr Kirwan, who has spent two days in the witness box, said Mr Corrigan regularly contributed intelligence reports "of substance".
It was later confirmed he submitted around 90 intelligence reports between 1984 to 1987, but that the flow of information dropped off then.
The witness was asked by counsel for the PSNI if the report indicating "improper contact" with a person associated with the IRA was the same as an RUC report from 1985 expressing similar sentiments. Mr Kirwan said it was not.
The witness was involved in 2000 with then Chief Supt Sean Camon in investigating the claims of collusion but found no evidence to back them up.
The witness faced detailed questioning from Justin Dillon, senior counsel for the tribunal and Mark Robinson, counsel for the PSNI, about the adequacy of that investigation and an earlier one carried out the day after the killings by Asst Commissioner Ned O'Dea.
It was pointed out to him that many gardaí were not interviewed by Mr O'Dea during his investigation, while several politicians who claimed to know the names of the IRA mole or moles were not questioned by him or Chief Supt Camon in their investigation.
The witness, however, maintained that both investigations were appropriate and proportionate. He did not accept there were missed opportunities in both probes.
Judge Smithwick asked him if his views were held "out of loyalty" to colleagues but Chief Supt Kirwan disagreed.
The witness also told the tribunal that during his years in the gardaí he never heard any allegations around Dundalk and did not believe there had been collusion in the deaths of Chief Supt Harry Breen and Supt Bob Buchanan.
Together with the late Chief Supt Camon, Mr Kirwan interviewed Kevin Myers, then a columnist with the Irish Times, and journalist Toby Harnden, author of a book 'Bandit Country'.
Both made claims of garda collusion in several murders but having talked to both men Chief Supt Kirwan said it was his opinion that "there was a high degree of irresponsible journalism in both cases. There's no escaping that fact."
Neither had evidence to support the claims they had written, he said.
