IAN Paisley last night warned Prime Minister Gordon Brown of "very serious consequences" for devolved government, if the IRA was behind the murder of Paul Quinn.
But the Stormont Executive could be saved from collapse because the News Letter has learned that the PSNI and Garda have already concluded the IRA leadership did not sanction the killing.
While members of IRA families (or an IRA gang) were involved, police on both sides of the border have ruled out the death being given the go-ahead by the Provisionals' leaders.
A very senior security source said: "We are absolutely clear the IRA leadership did not sanction this. But there were members of IRA families there.
"So far, what is not established is whether they are IRA members themselves. Did IRA members carry out the killing?"
What police have decided is:
Mr Quinn was lured to his death at a farm outhouse near Castleblayney, just south of the border;
Among those who beat him to death were younger men, from IRA families (but it is not yet known if they are IRA members);
His death came amid a fall-out between republican criminal gangs in south Armagh during the last three weeks;
The killing was the culmination of a series of incidents involving these rivals, who are split along mainstream and dissident republican lines;
Mr Quinn was involved in fuel smuggling and other criminality, and in some of these incidents;
One altercation took place in a bar when he faced down men from IRA families;
Mr Quinn was later visited at his home and warned to leave the country;
He refused to go and ended up beaten to death.
First Minister Ian Paisley said he had warned the Prime Minister of "the seriousness of the situation".
Speaking after a briefing from Chief Constable Sir Hugh Orde he added: "If this murder was the work of the Provisional IRA then very serious consequences will flow from that. As a party we have made it clear that there will be no place in government for those associated with murder
" I encourage everyone to wait for the findings of the police, both in Northern Ireland and the Irish Republic. There will be no fudging of this issue and everyone must work to ensure that those responsible for such a callous murder are exposed and brought to justice."
DUP MP and Policing Board Member Jeffrey Donaldson also insisted his party would not avoid pulling the plug on Stormont if it judged this was an IRA murder.
He welcomed unequivocal condemnation from Gerry Adams and others of the death, and assurances of no IRA involvement, but said his party would makes its own call on the matter.
"Our party will not fudge this issue," he assured unionists.
"Let's be clear, we will listen to the PSNI, the Garda and make a definitive assessment, based solely on the cold, hard facts and not what other parties say."
Sinn Fein leader Gerry Adams said he is absolutely certain the IRA leadership had nothing to do with the murder.
"The people involved are criminals. They need to be brought to justice and it is fairly obvious to me that this is linked to fuel smuggling and to criminal activity.
"There's no republican involvement whatsoever in this man's murder."
Unionist sceptics, like MEP Jim Allister have said separating the organisation as a whole, from what its members do, is not on - adding they had heard this stuff from Sinn Fein before.
The Quinn family is blaming the IRA was and friend and ex-Sinn Fein man Jim McAllister said: "Not only the family, but the whole community think the IRA carried it out."
SDLP MLA Dominic Bradley added: "It's been said that during the assault one of the attackers said 'We are the law round here'.
"Many people living in south Armagh would draw their own conclusion about that."
Screams for mercy ignored by killers
Family blames IRA for murder