The Garda Síochána Ombudsman Commission will prepare a file for the Director of Public Prosecutions after questioning a Kerry-based garda about alleged drug dealing.
The Irish Times report that the officer, believed to be in his 30s, was arrested by Gsoc investigators on Friday night.
The arrest was made after they searched a Kerry hotel room and found evidence to support an allegation that the man was involved in drug dealing.
He was subsequently released without charge on Saturday.
The allegation claims that the officer has been selling liquid MDMA or ecstasy at parties.
Gardaí became suspicious when they noticed large numbers of needles missing from drink-driving blood testing kits at the officer’s station.
The matter was referred to Gsoc by garda management and a criminal investigation was launched.
The man was questioned at Mallow Garda Station before being released on Saturday night.