A north Belfast republican being questioned over the fatal shooting of a father of four in the city on Friday night has been released unconditionally.
Dee Fennell (34), a spokesman for the Greater Ardoyne Residents Collective (GARC), was questioned over the murder of Michael McGibbon (33).
He was quizzed at Musgrave Police station in Belfast and later released, a PSNI spokesman said.
Ulster Unionist leader Mike Nesbitt said this afternoon those who knew who killed Mr McGibbon had a responsibility to come forward.
“Once again a family has been plunged into mourning following a despicable murder,” he said.
“There are people out there who know who murdered Michael McGibbon and society demands that they speak out.
“There are no excuses for holding back - otherwise the murderers will be free to inflict more pain in the future.”
Stormont leaders earlier jointly condemned the shooting in north Belfast.
Northern Ireland's DUP First Minister Arlene Foster and Sinn Féin Deputy First Minister Martin McGuinness issued a joint statement saying their thoughts and prayers were with Michael McGibbon's family.
“The perpetrators of this attack have shown complete contempt for the local community and are trying to bring intimidation and fear on to the streets of north Belfast,” they stated.
“We reject their agenda and actions and urge anyone with any information to bring it to the PSNI.”
Earlier, Ms Foster called on communities to help rid the region of paramilitaries who use violence to mete out their version of justice.
She stressed the need for information in the wake of the murder.
Taxi driver Mr McGibbon was shot three times in the legs in an alleyway in the nationalist Ardoyne area on Friday night - 24 hours after two men came to his house to threaten him.
The attack took place at about 10pm in Butler Place near Emfield Street. The PSNI said the killing “bears all the hallmarks of a paramilitary murder”.
His wife Joanne, a nurse, tried to save him before he was taken to the city’s Royal Victoria Hospital, where he later died after undergoing surgery.
Ms Foster condemned the killers and insisted people in Ardoyne held the key to securing justice for Mr McGibbon’s family.
“It is really shocking to hear of such a murder and indeed the style in which it happened,” she said. “My deepest sympathy goes to the McGibbon family.
"The community in and around north Belfast hold the answers for the police in this matter. I would appeal to them to work with the Police Service of Northern Ireland [PSNI] to bring these people to justice."
She added: "This is a terrible tragedy. Of course Northern Ireland is in a much better place now than it was many years ago, but we still have to deal with this evil that is on our streets and I give my full support to the Police Service of Northern Ireland in order to do that."
Last year’s Fresh Start political agreement at Stormont contained “actions and strategies” to tackle paramilitarism, she added.
“We will work very hard to stop these people on the ground, but we need the help of the communities where these actions take place to bring this to an end, so I really do call upon the people of north Belfast to come forward with information.”
Ms Foster made the comments at a DUP election event in Belfast.