A man murdered in a gun attack in east Belfast overnight has been named as Kevin McGuigan Sr, who was a former member of the Provisional IRA.
Police said he was one of a number of suspects in the murder of Gerard Jock Davison, who was shot dead in May.
Mr McGuigan was shot at Comber Court in the Short Strand on Wednesday night.
Sinn Féin has denied speculation that Provisional IRA may have been involved in his murder. The DUP said there will be "repercussions" if that is the case.
Mr McGuigan, a father-of-nine, was treated by paramedics at the scene before being taken to Belfast's Royal Victoria Hospital, but he died from his wounds.
Heavily armed officers set up a cordon in the Short Strand within minutes of the gun attack, which was reported shortly before 21:00 BST.
Police have begun a murder investigation and appealed for anyone with information to contact them.
The victim's elderly mother, Margaret McGuigan, told the BBC that her son's killers would have to live with what they had done.
She added there had been "too many murders" in the area and that she hoped her son's would be the last.
Mr McGuigan had been questioned by police after the murder of Jock Davison in the Markets area of Belfast three months ago.
Mr Davison, 47, was a former IRA commander and a former friend of Mr McGuigan.
The IRA pair were also founding members of the paramilitary group Direct Action Against Drugs (DAAD), which killed more than a dozen alleged drug dealers.
They were later involved in a feud, and Mr McGuigan was shot several times in a so-called punishment attack.
It was claimed that Mr Davison gave the order for that attack on his former friend.
Politicians have condemned the murder and said Mr McGuigan's killer must be caught.
Northern Ireland's First Minster and DUP leader, Peter Robinson, was asked if he was concerned that IRA or former IRA members may have carried out the attack.
"I think everyone should be concerned that would be the case," Mr Robinson said.
"We will speak to the PSNI to see what their findings are in terms of the involvement of any organisation. But let's be very clear, there will be repercussions if that was found to be the case."
But leading Sinn Féin member Alex Maskey said he had "no concerns about IRA involvement" in Mr McGuigan's murder.
"I don't accept for one second that the IRA has been involved in this, it just doesn't register at all," Mr Maskey added.
"We're calling for calm, we're calling for respect for this particular family at this time in the midst of their grief and we're cautioning against unhelpful and unwelcome speculation."
Justice Minister David Ford said: "Those responsible for this appalling crime have left a family grieving and a community in shock.
"There is no place for the gun in our society and it is time to stop these attacks."
Jim Allister, leader of the Traditional Union Voice (TUV), said there must be no cover-up in the murder investigation.
"Police, politicians and all who value truth and justice must face, not fudge, the truth, however uncomfortable it might be," he said.
The Social Democratic and Labour Party (SDLP) leader, Alasdair McDonnell, said on Twitter: "Those behind this savagery on our streets must be brought to justice."