An IRA statement urging the killers of Robert McCartney to take responsibility for their actions has been welcomed by his family.
Robert McCartney, 33, was killed near Belfast city centre
Mr McCartney, 33, was stabbed after a pub fight in Belfast two weeks ago. His family said republicans were pressuring witnesses not to talk to the police.
His sister Paula said it was a way of removing obstacles for witnesses.
A man arrested in connection with the killing was released without charge by police on Thursday.
In a statement, the IRA said no-one should hinder Mr McCartney's family "in their search for truth and justice".
"The statement made by the IRA strongly supports the family's position with regards to justice and truth prevailing," she said.
"We appeal to anyone who can help us as a family to bring an end to this nightmare and in doing so set us free to begin our grieving for Robert."
Meanwhile, Sinn Fein justice spokesman Gerry Kelly told BBC Radio Ulster on Thursday that people with "reservations" about the PSNI must be allowed to help the McCartney family.
"I would like to see the family getting justice in this, and the people who were involved in this brutal slaying should be rejected entirely by the community... and brought to justice," he said.
In a letter to a Belfast newspaper, one of Mr McCartney's aunts said intimidation and threats came "from the highest level of Sinn Fein and IRA".
Margaret Quinn said she feared for her own son's safety after writing a letter to the Irish News condemning the killing of his cousin.
She wrote: "If an innocent, well-respected young man like Robert, out for a drink with friends, can be pounced on and fatally stabbed within minutes of entering a pub - in full view of 72 witnesses - simply for being in the wrong place at the wrong time, then we, the family, must speak out for justice."
In response, Mr Kelly said the threats did not come "from the higher echelons of Sinn Fein".
"What the leadership of Sinn Fein has done has (issued) very strong words publicly so that every republican and member of the community can read them," he said.
He said the party was "on the same side" as the family.