A GARDA faces dismissal from the force if he is found guilty of serious disciplinary charges after an alleged row with a colleague while on protection duty outside the United States Embassy in Dublin.
Last night an internal investigation was under way into the incident, which has already resulted in the suspension of two gardai based at a south central city station.
The two gardai are both in the uniformed branch of the force but had been transferred temporarily into the plain clothes section to man a security post outside the Embassy in Ballsbridge.
They were both armed with standard Smith and Wesson handguns while on the 12-hour shift with a uniformed garda outside the Embassy at the weekend.
It is alleged that one of the temporary detectives began drinking heavily during his breaks and was later involved in a row with the other armed garda outside the Embassy.
The detective then handed his gun to the uniformed garda and drove away before his shift had ended.
He was subsequently stopped by a garda patrol at Ballymun at around 5.20am and arrested on suspicion of drink driving.
His firearm was returned to his garda station by a colleague when the shift ended at 7am.
It is understood that the incident at the Embassy was witnessed by US Marines who were on security duty inside the building.
The Garda authorities have appointed Supt Philip Moynihan of Bray garda station to head the internal investigation while the two gardai remain suspended from duty.
One garda faces the possibility of being charged with a drink driving offence in the criminal courts and disciplinary charges could include abandoning his post.
If he is found guilty of serious breaches of discipline and a criminal offence, he could be sacked from the force.
Armed guard duty outside the US Embassy is regarded as one of the most sensitive security postings because the building is at the top of the list of locations likely to be threatened or attacked.
The incident has added to the woes of the Garda force, which is already under severe pressure because of the severe criticisms voiced in the second Morris report and the likelihood that more sensational allegations against members of the force will be raised during the next two modules of the tribunal.
Up to now, those at the centre of the criticism were all serving in the Donegal division at the time of the offences under the Morris spotlight.
But it is expected that gardai from outside the division will also be implicated in the web of allegations during the upcoming hearings.
The Embassy incident will also be a source of embarrassment for senior officers because of the close links between the force and the US law enforcement agencies.