A LEADER of the New IRA alliance is believed to have ordered the pub car park hit on dissident terrorist Peter Butterly.
Butterly (35), the former head of the Real IRA in the Louth region, had been sidelined by the alliance in the past few months because they suspected he had pocketed some of their funds.
Gardai are satisfied that the Armagh-based leader chose a Dublin northside unit to carry out the shooting.
Butterly was lured to his death after receiving a phone call to meet some of his former associates.
Gardai were last night continuing to question five men, two from Balbriggan and the others from Raheny, Tallaght and Blanchardstown, about the killing.
All five were detained near the car park of the Huntsman Inn in Gormanston, Co Meath, where Butterly was shot dead around 2pm on Wednesday.
They were arrested by armed members of the Emergency Response Unit and the National Surveillance Unit, who were monitoring the movements of some of the suspects.
The officers did not see the shooting, but were quickly on the scene.
Butterly was sitting in his Renault Megane when two men drove into the car park in a Toyota Corolla. One of the attackers fired two shots into the Megane, and as Butterly struggled to get out and flee, two further shots were fired.
He fell to the ground as the two men sped off, throwing a 9mm handgun out of their car and over a hedge.
The Corolla was rammed by a garda car and the two suspects, aged 31 and 22, were arrested.
Two other men were detained when officers stopped an Opel car, and the fifth man was held after he arrived at the scene on foot. The three are aged 42, 33 and 28.
Two of the suspects are well-known to gardai as suspected dissidents and have been questioned in the past about other incidents including attacks ordered by another Real IRA faction boss, Alan Ryan, who was shot dead by drug traffickers last September.
One of the five men held is understood to have been injured in a shooting on the northside of Dublin last year.
Gardai believe two of the attackers were tasked with carrying out the shooting, two with setting fire to the getaway car and disposing of the weapon and the fifth was being deployed as a lookout.
Anti-terrorist officers believe Wednesday's murder is the latest in a series of shootings carried out for the alliance leadership.
They want to put their own discipline on members of the Real IRA, who were thought to have been skimming the profits from extortion and other fundraising crimes.
The formation of the alliance last summer has resulted in an increase in violence in the North, including the murder of prison officer David Black and the foiled mortar bomb attack on a police station in Derry last weekend.
Some of the former Provisionals who have joined the Real IRA and Republican Action Against Drugs in the alliance have been blamed in the past for the murder of PSNI constable Ronan Kerr in Omagh in 2011 and the attempted murder of another constable and GAA player, Peadar Heffron, in Antrim in 2010.
A white Citroen Berlingo van, which had been fitted with a launch pad for the planned mortar bomb attack in Derry, had been bought in Dublin earlier this year.