The 44-year-old detective arrested and questioned about a hit-and-run killing of a cyclist on the Naas dual carriageway on Monday morning has been released pending a decision on charges against him.
The officer, who is attached to the National Bureau of Criminal Investigation (NBCI), was questioned about the death of Mr Gerard O'Neill (36), from Clondalkin, who worked as a caretaker.
Mr O'Neill's body was found beside his mangled bicycle near the SDS centre on the dual carriageway by a passing motorist at about 2.45 a.m. on Monday. Garda believe Mr O'Neill's body could have lain on the roadside for an hour before he was found.
The garda is understood to have been driving home in an unmarked Garda squad car. The car, which was marked out of the NBCI car pound in the detective's name, was found abandoned in Rathcoole. Officers from Clondalkin Garda Station called to the officer's house and he presented himself at another Garda station at 3.30 p.m. on Monday.
The detective has been suspended from duty.
A file on the case is being completed and will be submitted to the Director of Public Prosecutions (DPP). It is understood the DPP will be considering whether to bring a charge of dangerous driving causing death.