The ombudsman is likely to set up an investigation into the matter, but it will first wait until it receives a report ordered by Garda Commissioner Fachtna Murphy.
It is understood the complaint centres on the Garda investigation into the original public order incident.
This involved a constituent of Mr Sargent, Dominic McGowan, on whose behalf the deputy had made representations to gardaí.
Mr McGowan was involved in a heated row with a parent of a young girl he was remonstrating with over interfering with a road sign in September 2007.
Mr McGowan was charged with, and convicted of, threatening and abusive behaviour, and was fined €500, while his neighbour, Stephen Mulvany, was sentenced to four months for assault and breach of the peace, which he has appealed.
In a statement yesterday, the Garda Síochána Ombudsman Commission (GSOC) said: “The Garda Ombudsman has received a complaint relating to this matter and is considering the issues raised in that complaint to ascertain its admissibility and the appropriate form of investigation.”
The commission refused to comment the identity of the complainant, but sources outside the commission indicate it is someone closely linked to the original incident.