'He hadn't even taken out his gun . . . when one of them let off a shot and blasted him'

Gardaí believe at least one of the gang remained in the vehicle as the getaway driver but that the other three men got out of the car during the attack. It was unclear how many were armed.

While Det Garda Ryan was a witness to the events he did not see the full incident and the credit union staff who saw what happened were said to be “severely traumatised”. The incident was over very quickly and it was not until the raiders had left that Det Garda Ryan established his colleague had been fatally injured.

Alarm raised

Det Garda Donohoe lived in the townland where he was shot and his son and daughter, who are six and seven, attend school across the road from the location of the shooting.

The alarm was raised from the scene immediately and Garda vehicles in the region sped into the area in an effort to intercept the escape of the raiders in their car.

North of the Border the PSNI reacted in a similar fashion in an effort to put in place a cordon of manpower that might frustrate the escape.

The getaway vehicle is believed to have driven to the Ballymacscanlon roundabout within 2km of the crime scene, from where the raiders would have left the Cooley Peninsula and the M1 could have taken them in the direction of Dublin or north over the Border.

Gardaí believe the car was driven north of the Border.

There is now a strong cross-Border element to the investigation being led from Dundalk Garda station, where Det Garda Donohoe was based and where his wife, Caroline, also works as a member of the force.The dead man’s two brothers are also gardaí and are based in Swords, north Dublin, and in Navan, Co Meath.

Scene sealed off

The scene of the killing remained sealed off yesterday and was undergoing a forensic examination by members of the Garda Technical Bureau.

Garda search teams were cutting back undergrowth around the credit union and its car park as part of a thorough search for the murder weapon or any other items that may have been discarded.

Gardaí have also taken CCTV footage from the credit union and other commercial and residential premises in the area in the hope of piecing together the gang’s movements before and after the killing.