Information in a key statement during the investigation into the death of Raphoe cattle dealer Richie Barron "had to come from a Garda source", a senior officer has said.
The November 1996 statement by Mr Noel McBride was withdrawn almost a year later - he said an informer put him up to making it.
Supt John McGinley said his first inkling that the statement was untrue was not until the end of the following summer. He said he got a phone call from Garda John O'Dowd on November 29th, 1996, and was told a man was in the station who was going to make a statement.
He was introduced to Mr McBride, who had been arrested earlier that day on theft charges. He was told Mr McBride was going to make a statement that he saw Mr Frank McBrearty jnr and his cousin Mr Mark McConnell at a critical time. Complaints of Garda harassment from the McBrearty family led to the setting up of the tribunal.
Supt McGinley said he would not agree with a description of Mr McBride as "a gormless old devil" and "of limited intellect" but "I think you'd have to conclude that somewhere along the line he was tutored and helped".
Supt McGinley was also questioned about a witness who changed a statement, thus removing an alibi for Mr Frank McBrearty jnr. Ms Josephine Simpson, who worked for the McBrearty family, originally told gardaí she gave a set of keys from the McBrearty pub to Frank McBrearty jnr at 12.45 a.m. However in subsequent statements, she said she gave the keys to his father, Mr Frank McBrearty snr.
Ms Simpson was one of Mr McBrearty's staff. When gardaí went back a second time to check the conflict, she said she gave the keys to Frank McBrearty snr.
She said this when interviewed by gardaí a third time and also when interviewed by private investigator Mr Billy Flynn.
"It is being inferred that the guards got her to change her statement, well, I can't say that," Supt McGinley said. He said that Ms Simpson identified Mr Frank McBrearty snr three times and gave statements to three different gardaí and to a private investigator.
Mr Peter Charleton, for the tribunal, asked if there was a mood of "let's get them" in the incident room investigating Mr Barron's death. "I would say that there was no such mood," he said.