No paramilitary group claimed responsibility for the killing of Davison, who was shot at short range outside his house in the Markets neighborhood of south-central Belfast.

Witnesses said Davison's three children had seen his body and ran away screaming.

Detective Chief Inspector Justyn Galloway, who was leading the investigation, told the Belfast Telegraph newspaper it was a "cold-blooded murder carried out in broad daylight."

Davison had been an Irish Republican Army commander who was accused of ordering his comrades to kill a man, 33-year-old Robert McCartney in 2005, over a bar room disagreement.

McCartney had been fatally stabbed outside the pub and IRA members allegedly hid surveillance videos and cleaned up forensic evidence. McCartney's sisters alleged at the time that Davison had made a throat-slitting gesture.

Rejection of violence

The apparent involvement of paramilitaries in the non-political killing was seen as an abuse by many within Northern Ireland's Catholic community. Support for the group's campaign of violence was already diminished as the British and Irish government and both sides of the community - Loyalist and Republican - made strides towards a lasting peace process.

Davison, 47, had supported Irish nationalist political party Sinn Fein's peace strategy in recent years, the Belfast Telegraph said. He had always denied a role in the killing of McCartney.

Sinn Fein official Alex Maskey said the party would not speculate on who carried out the killing and called Davison "a longstanding republican" who was "very well regarded."

The Provisional IRA has been observing a 1997 ceasefire as part of the Northern Irish peace process. However, splinter groups still exist and mount attacks, and feuds can turn deadly.

rc/jil (AP/dpa)