A top Irish police officer who became head of the force ignored allegations a sergeant was colluding with the IRA, a major corruption inquiry has heard.
The late Eugene Crowley was told in 1987 that a Garda officer was "unnecessarily assisting" the terror group but appeared uninterested, a retired chief superintendent has claimed.
The Smithwick Tribunal also heard claims Mr Crowley was warned of death threats against an RUC officer up to a year before he was killed in an IRA ambush. Superintendent Bob Buchanan was murdered with Chief Superintendent Harry Breen near the border after a meeting at Dundalk Garda station in March 1989. The tribunal is investigating allegations of IRA/Garda collusion.
Retired Garda chief superintendent Tom Curran said he wrote to Mr Crowley, the then assistant commissioner in charge of crime and security, at Garda headquarters in Dublin about a threat against Mr Buchanan's life between March and October 1988.
Mr Curran, who was in charge of border security in the Monaghan region from 1981 to 1999, told the tribunal he regularly held meetings with Mr Buchanan.
He revealed that in the first half of 1987 he was told by Mr Buchanan the RUC had information that then Dundalk-based sergeant Owen Corrigan was "unnecessarily assisting" the IRA.
Mr Curran - who stressed he had no evidence of collusion - said he visited Mr Crowley the next time he was in Dublin.
"When I went in he was reading a file and I told him the purpose of my visit and I told him the information that was passed on to me by Bob Buchanan and other bits - hearsay I had heard about Owen Corrigan," he continued.
"We discussed activities in Monaghan but he never mentioned anything about the conversation I went there to tell him.
"He didn't acknowledge it in any way or ask questions about it," he added.
Superintendent Bob Buchanan and Chief Superintendent Harry Breen were the two most senior members of the RUC murdered during The Troubles. They were ambushed in an IRA gun attack in 1989. Supt Buchanan, a father-of-two, died at the wheel of the unmarked car as he attempted to put it into reverse. Chief Supt Breen, who also had two children, was found dead on the roadside.