The sisters of IRA murder victim Robert McCartney have said they believe the Provisionals were responsible for killing a Belfast father-of-nine but doubt that his assassins will ever be brought to justice.

Catherine McCartney said: "In my opinion, the Provos were responsible and that is bad news for the McGuigan family because, in our family's experience, the PSNI take a kid gloves approach to murders carried out by the IRA.

"Kevin McGuigan was killed just three months after Jock Davison. That stinks to high heaven. We will be watching what the police say and do very carefully over coming weeks.

"It seems unbelievable that the PSNI, and the intelligence services, did not know Kevin McGuigan's life was in serious risk and did not act to protect him."

In Provisional ranks, Kevin McGuigan (53) was the chief suspect in the murder of ex-IRA commander Davison in the Markets area of Belfast in May.

A former senior local IRA member himself and key hitman in the Provo cover group, Direct Action Against Drugs, McGuigan parted ways with the Provos in acrimonious circumstances more than a decade ago.

Last night ex-IRA prisoner Anthony McIntyre revealed how McGuigan had previously contacted him to say he believed his life was under threat from the Provos.

Catherine McCartney said her family knew the murder victim, who had been a neighbour in the Short Strand.

"I hope my suspicions are wrong and there will be no cover-up regarding his killing," she said. "I sincerely hope the McGuigans receive justice, but given the rottenness at the heart of policing, and the politics of the peace process, I think it's unlikely they will."

Robert McCartney (below) was stabbed to death by IRA members outside Magennis's bar in Belfast city centre in 2005.

No one has ever been convicted for his murder. Eyewitnesses said that his killers were acting on the orders of Davison.

McIntyre, who first met Kevin McGuigan when they were prisoners in the Maze almost 30 years ago, claimed his murder "has the IRA's fingerprints all over it".

He said: "This is their modus operandi, whether their own people have done it or they've farmed it out to another group.

"I believe the IRA was sending out a message: 'F*** with us and we'll take you out with massive force'. The IRA leadership is worried that there are people out there with grievances who might be thinking of taking out guys far more senior than Jock Davison.

"What we saw in the Short Strand on Wednesday night was the IRA at its most effective and ruthless. It's not even hiding, it's hiding in the open."

McIntyre said that after their release from prison, McGuigan had contacted him when he was in Belfast's Royal Victoria Hospital recovering from a punishment attack ordered by Davison. He had received a "six pack" - shot in the ankles, knees and elbows. It was a humiliating attack on a former friend. "Kevin asked me to come and visit him and I did," McIntyre said.

"I was pretty outspoken against IRA actions at the time and I think he sent for me because he wanted an ally. He was absolutely furious about the IRA attack on him."

McGuigan contacted McIntyre again three years ago with serious concerns that his life was in danger.

"He wasn't afraid for himself, Kevin was just one of those people who isn't afraid, but he was worried for his family's safety. He talked about going public with certain information. He wanted to release material publicly, but he never did. He totally believed that Jock Davison was an informer, a view I did not share. Kevin had information about an IRA rocket attack which he felt was crucial."

McIntyre said that McGuigan's later clashes with the IRA leadership were totally out of keeping with his relationship with the Provo top brass in jail: "In Long Kesh, he was very on-message with the leadership, always pushing the Provo line, whereas I was a critic.

"I remember him trying to get prisoners to fill in census forms in 1991. I was against doing that. I said to him: 'Sure the IRA shot dead Joanne Mathers in Derry for what you're doing now'. And he just replied, 'This is what the movement wants'."

McGuigan had been jailed for the kidnapping and false imprisonment of a British soldier along with Ardoyne republican Martin Meehan.

The Territorial Army recruit had been abducted by the IRA on July 12, 1986, and imprisoned in a house in north Belfast before being freed in a rescue operation by the British Army.

A court heard that the soldier had suffered a broken jaw and been bound and blindfolded in preparation for being shot dead despite the IRA unit falsely claiming they had been about to hand him over to a priest.

McIntyre said that McGuigan remained "very proud" of his IRA past despite his parting of ways with the Provo leadership.

"He was a strange character, a bit odd. There was no doubt that beneath the placid surface lay a very violent energy.

"I don't know whether or not he killed Jock but he was certainly capable of it, and the animosity would have been there."

McIntyre said that it was "total madness" that McGuigan continued to live in the Short Strand following Davison's murder and IRA rumours connecting him to it.

Belfast Telegraph