The Smithwick Tribunal yesterday excluded members of the public as it sat to hear security-sensitive evidence from retired British army brigadier Ian Lisles.
Judge Peter Smithwick said he would consider releasing a transcript of Mr Lisles’s evidence, once he had the opportunity to consider it carefully.
Mr Lisles, who previously gave evidence to the tribunal in September, was posted to south Armagh in 1989, a few months after two senior RUC officers were killed in an IRA ambush.
Chief Supt Harry Breen and Supt Bob Buchannan were shot minutes after leaving a meeting in Dundalk Garda Station.
They were the most senior police officers shot during the Troubles.
The tribunal is inquiring into suggestions certain gardaí colluded with the IRA in the murders.