There have been calls in some political circles for the garda ombudsman to investigate the incident after it was revealed the garda was taken to a station 10km away from the crash scene in Lucan village to be breathalysed.

The car struck O'Toole, who was returning home after a night out, at around 5am on Sunday 4 March while the garda was returning from a night out with other garda colleagues. He was taken to Harcourt Terrace garda station to be breathalysed as there was no machine in Lucan station.

The garda passed the breath test and called his uncle, a garda inspector in Santry station, who gave him a lift home.

However, a garda compiling a report wrote that the officer was "released into the custody of his uncle".

Senior officers are furious over this sentence, saying it undermined their attempts to ensure that the investigation was as transparent as possible.

One source said: "The fact is that there was no intoxiliser in Lucan and we didn't want to take the garda to Blanchardstown because he serves there and it would not have been appropriate.

"The garda passed the breath test and phoned his uncle who just happened to be a guard.

"He gave him a lift home but he was never ever in his custody. It's frustrating because it adds to the pain for the O'Toole family and for the young garda involved in what was a tragic accident."

A post-mortem on the body of Derek O'Toole, whose funeral took place last week, showed he had not been assaulted prior to being struck by the car.

The Clondalkin native had spent the night socialising and had alcohol taken.

The garda is said to be extremely traumatised over the incident and has not yet returned to work.