The IRA informer, Mr Eamon Collins, had so many enemies it was impossible to pinpoint who killed him, republican sources along the Border said last night.
"You could fill Long Kesh with the suspects," said one source.
The RUC yesterday began a murder inquiry after Mr Collins's body was found, stabbed and badly beaten, outside Newry, Co Down, on Wednesday. Chief Insp Eddie Graham said Mr Collins had suffered a horrendous death. "It is more of a kind of crime related to primitive man than a society at the end of the 20th century," he said.
"We have not ruled out anything," Mr Graham said. Although no paramilitary group has admitted responsibility, it is widely accepted in republican circles that either the Provisional IRA or dissidents were involved.
"You would have to be living in cloud cuckoo land to think anybody else did it," a republican source said. But it could be some time before an accurate account of the murder emerged, he added.
"Eamon Collins was very unpopular among republicans and although nobody might publicly claim it, privately everyone will be wanting to claim it," he said. There has been widespread political condemnation of the murder.
But there was a mixed reaction in Newry yesterday.
A neighbour of Mr Collins on the Barcroft Estate said: "What happened him was horrible. He should have been allowed to live his life in peace. We are meant to be putting the past behind us." Another neighbour was less generous: "If Eamon Collins had moved down South and just led a quiet life, nobody would have bothered him. But he wanted a high public profile."
The First Minister, Mr David Trimble, yesterday blamed the Provisional IRA's south Armagh brigade for the killing. He said it was a breach of the ceasefire which the British government must address.
But several theories are circulating among republicans as to the identity of Mr Collins's killers and at what level the attack was sanctioned.
Attention is focused on a former Provisional IRA chief-of-staff, who is still on the army council, and who was angered by Mr Collins's actions in the past year. Although the army council might not have approved the killing, republican sources believe the leadership would turn a blind eye if this man ordered it.
The main target of Mr Collin's recent public statements had been "Real IRA" leaders whom he described as having "ageing, potbellied, drink-induced egos". Republican sources said the personal nature of his attacks on dissidents had caused much enmity.
"After Omagh he went on television basically urging the Provos to take the dissidents out," said a source. Republican sources have also said that a former close associate of Mr Collins in the Provisional IRA wanted to kill him.
One source claimed this man was "suspicious" of Mr Collins shortly before he became an informer. The man remains in the Provisionals although he is rumoured to be sympathetic to the "Real IRA".
Mr Collins regularly voiced strong views against this man whom he believed tried to kill him in a hit-and-run incident two years ago, according to a friend of the dead man.
At first, it was believed Mr Collins had been killed in a hit-and-run incident but it is now understood he was abducted while walking his dogs, beaten with a blunt instrument, and then stabbed.
He was so badly mutilated that police advised his wife not to identify his body.