Officers investigating the death of Richie Barron were aware of a plan to arrest petty criminals in the Raphoe area and question them about what they saw, giving cover to a witness who made a crucial statement in the case, the tribunal heard.
Garda Martin Leonard told the tribunal he was custody officer in Letterkenny Garda station on November 29th, 1996, the day Noel McBride was arrested on suspicion of theft of an aerial. Garda Leonard said that after Mr McBride made a statement admitting the offence, he was released from custody at about 10.30pm.
Later that night, Mr McBride made another statement, saying he saw Frank McBreary jnr and Mark McConnell in a car park at the critical time Mr Barron died.
A year later Mr McBride withdrew his statements and said he was put up to making them by William Doherty, an informer.
Garda Leonard said he knew Mr McBride was "going to remain on voluntarily" after he was released from custody. The garda said he trusted his colleagues and that if Mr McBride had information about what happened in Raphoe, that was important.
Garda Leonard said it was "a lie" that Supt (then Insp) John McGinley was not in the interview room when Mr McBride was questioned about what he saw.
"I'm disgusted that senior officers lie like that," he said.
Garda Leonard said the other arrests of petty criminals on November 29th, 1996, were "sham" arrests.
"Afterwards I heard that it was an umbrella, that it was to protect McBride. It was being used as a mechanism, that McBride had information and they wanted to cover McBride and this was a smokescreen."
Garda Leonard said he didn't know who had organised the scheme, because he was not part of the incident room.