Garda Keith Harrison first met with GSOC in August 2014 and was told a probe into his complaints of malpractice in the force would be immediately investigated.
Earlier this month, his solicitor wrote to GSOC chair Mary Ellen Ring, complaining that virtually no progress had been made.
In a response seen by the Irish Examiner, a GSOC investigator informed Garda Harrison and the solicitor that they are still awaiting compliance on a request for documents before it will be possible to advance the investigation.
The Irish Examiner understands members of GSOC have expressed frustration at the extent of the delay over the supply of information.
Garda Harrison had complained of malpractice in his previous posting in the Midlands, where he had prosecuted a fellow officer for drink driving, in a case that was ultimately dismissed in the District Court. He also complained that he had been subjected to harassment since he made his official complaint.
During that time, he has been subjected to a disciplinary inquiry, although the grounds for the inquiry are unclear. He was also told that he was to be the subject of a possible criminal investigation but that was halted after he brought judicial review proceedings.
Garda Harrison has been on sick leave since he made his complaint and is anxious to get back to work, but claims that any return has been blocked.
“Our client is presently on sick leave and his employer have effectively done everything in their power to force him to resign as a member of An Garda Síochána. The failure of the commission to advance their investigation has seriously undermined and prejudiced our client’s position in circumstances where he and his partner and their children are suffering ongoing victimisation and harassment,” his solicitor wrote in the letter to Ms Ring.
The reply from GSOC indicated that the inordinate delay was attributable to the failure of gardaí to supply information.
Last week, Ms Ring told an Oireachtas committee that GSOC had experienced delays in getting information from the gardaí. She said it was an ongoing difficulty and GSOC lacked the powers required to impose a penalty if the information was not promptly provided.