The Garda Ombudsman Commission has begun a public interest inquiry into the evidence given by a number of garda witnesses during the trial of another garda for assault.
Garda Drew Morgan was convicted last Friday at Dundalk District Court of assaulting Derek Bradley from Clogherhead in Co Louth at Drogheda Garda Station two years ago.
He is appealing the conviction.
The court heard Mr Bradley had been detained on suspicion of drink-driving.
At 1am on 6 February 2011, Garda Morgan, who was not involved in the arrest, pushed Mr Bradley from behind into a radiator after he asked that his handcuffs be loosened.
Judge Alan Mitchell sentenced Garda Morgan to three months in prison.
The judge described the evidence of other gardaí in the case as "disturbing to say the least" as some appeared to have "looked away at that moment", had their "views blocked" or had "hazy recollections".
The judge said it brought to mind "see, hear or speak no evil".
He said it was not the garda's finest hour and there may be persons who heard the evidence who may feel it is appropriate to investigate further.
The Garda Commissioner appointed Assistant Commissioner Kieran Kenny to carry out an investigation into the matter.
However, the three members of the Garda Ombudsman Commission met to review the case and decided to establish a public interest inquiry.
The Ombudsman's investigation is to determine if any garda or reserve garda witnesses could have committed an offence or an act of indiscipline in the provision of evidence under oath or in preparing to give evidence at the trial.