JUSTICE Minister Alan Shatter says the gang that murdered Detective Garda Adrian Donohoe must have known gardai would be at the credit union.
The gang that robbed the credit union were "intent on murder and mayhem".
The Irish Independent reported this morning that gardai are satisfied their murdered colleague was lured into a trap and deliberately ambushed.
Mr Shatter said he was confident the gang would be brought to justice.
He said the murder was "an attack on all members of the force" and on the State.
"Everything that is necessary to bring these people to justice will be done," he said.
But Mr Shatter said if the gardai were not there, then a member of the credit union staff could have been killed. He said the robbery was clearly pre-planned.
"Quite clearly the gang that was engaged in this event, on the assumption there was some pre-planning, must have known there was some garda security for cash coming from the credit unions.
"They were quite clearly armed. They gave Garda Donohoe no chance of any description.
"This man had no chance to say anything and even to reach for his own weapons. He simply was shot in circumstances where there was no hope of survival," he said.
"It's quite clear this was a group of people intent on murder and mayhem, they had no respect for human life. It may well be the case that if the gardai had not been there, a member of the credit union could have lost their lives.
"So quite clearly these people had no compassion, no moral compass of any description and it is of the utmost importance that they be tracked down, the Commissioner and all those working on this investigation are dedicated to achieving that outcome," he added.
In a statement, the Garda thanked the public for the outpouring of support.
" An Garda Siochana would like to acknowledge the huge amount of public support we have received since the tragic event," a Garda spokesman said.
"This support means a great deal to the family, friends and colleagues of Detective Garda Adrian Donohoe and is a source of great comfort at this difficult time."
The force renewed its appeal for anyone who saw anything suspicious in the area of the killing on Friday night, or a dark-coloured car driven erratically on the Republic's M1 motorway close the border to get in contact.