It follows claims officer attended party with Gerry Hutch.
The Minister for Justice has requested a report from the Garda Ombudsman following the resignation of an officer amid claims he was at house party with Gerry Hutch on Monday
Minister Simon Harris says it's "a serious matter which needs to be investigated".
It's understood the officer told a number of people that he had been at the party, which Mr Hutch attended.
The claim was subsequently reported to senior management at GSOC and the senior investigator resigned.
Paul Healy, chief reporter with the Irish Daily Star, says the officer has been involved in several major investigations.