Retired Sligo garda John Nicholson was trenchantly criticised for lying to the tribunal.
Bernard Conlon was retained as an agent by Det Sgt John White through Nicholson. He took a statement from Conlon about being found drinking after hours, knowing that he had been planted as a witness.
Nicholson co-operated with White in procuring forged certificates and the report said he lied about these events to the tribunal.
"Mr Nicholson lied about his involvement in the events to the Carty Garda internal investigation team, his colleagues, his deceased colleague's family and to the tribunal, though given every opportunity to assist in ascertaining the truth," the tribunal said.
Another garda, Det Garda Paul Casey, wrote out the body of one of these forged certificates but was not culpable of any wrongdoing. He did so to help Garda Nicholson because of his severe arthritis.
"It was credibly represented to him that Garda Nicholson had a crippling pain in his hand on that day and needed help in a routine matter. Garda Nicholson attempted to use the hearings of the tribunal to gain advantage from and debase Garda Casey's act of kindness," it said.
The tribunal was satisfied that White and Nicholson told lies in their evidence to the tribunal.
The tribunal said there was no evidence to support the allegation made by Nicholson that his colleague, the late Garda John Keogh, was in any way involved in the forging of the certificates of loss of earnings.
"I am satisfied that his evidence in relation to the late Garda Keogh constitutes an unedifying attempt to minimise his guilty knowledge in respect of these certificates; it was a mean-spirited and self-serving pretence in which he persisted in the face of clear evidence contradicting his evidence before the tribunal."
John Nicholson was born in Boyle, Co Roscommon and joined An Garda Síochána on March 29th, 1967.
He was transferred in 1972 to Sligo, where he remained until 2002.
During the course of his career Nicholson was highly regarded in his community, which he served as a member of the Garda and as a private citizen.
The tribunal was made aware of numerous testimonials in support of his character and good works within the community when residing in Sligo.
"Arising out of this sorry affair, Garda Nicholson was prosecuted and pleaded guilty to three counts of uttering forged documents following a successful investigation by the Carty team," it said.
He applied for retirement, which took effect from September 4th, 2002.
WHAT THE TRIBUNAL SAID: "The fact that Mr Nicholson has abused this man's name in death and tried to hide behind him is disgraceful."