The senior officer in charge of the Donegal division during the Richie Barron investigation has said false allegations demoralise gardaí and undermine public confidence in the force.
Retired Chief Supt Denis Fitzpatrick said he did not believe an allegation by former Det Sgt John White that conversations between members of the extended McBrearty family and their solicitors were bugged by gardaí during their arrests in December 1996.
"There was a pattern of spurious mischievous reports being made, either through the media or directly to the guards," Mr Fitzpatrick said.
"This was another one of the reports on the media to discredit guards, to take heat off other people.
"What would happen then is you absorb resources, you undermine the guards that are doing the investigation. You demoralise them, you tie up resources in it.
"It just soaks the energy out of investigation teams. It affects public confidence, because you put these things into the media and they are not true. And you have an obligation not to be putting untruths in the media, remember that, Mr White." Mr White, who cross-examined Mr Fitzpatrick on his own behalf, said he did not put untruths in the media.
The tribunal is examining allegations by Mr White that privileged conversations were covertly recorded during the investigation into the death of hit-and-run victim Richie Barron, on the day that eight people were arrested, including cousins Frank McBrearty jnr and Mark McConnell.
Mr Fitzpatrick said he was not aware of a direction from the Garda Commissioner that covert taping of suspects might be allowed in "extraordinary circumstances" and was not aware of such a plan during the Barron investigation. Solicitor Paudge Dorrian said he learned of the bugging allegations from his client Mr White and decided to go public with them because Mr White told him senior gardaí knew it would not be investigated. He had acted for gardaí on an unrelated case and "the guards would not discuss anything with me in Letterkenny barracks, they always insisted on going outside".
However, he said no garda ever told him he was being taped.
"The information that I had was that everybody in the higher echelons of the Garda Síochána knew about this, but they were going to deny it," he said.