Detectives in Belfast have released a man being questioned about the murder of father-of-two Robert McCartney.
Robert McCartney, 33, was killed near Belfast city centre
Mr McCartney, 33, was stabbed to death near Belfast city centre on 30 January following a row in a bar.
Police say the man has been released pending further enquiries. He was arrested on Wednesday after going to a police station with his solicitor.
In a statement the IRA has said it offered to shoot those involved in Mr McCartney's killing.
Police officers have posted fresh appeals in the Short Strand area - where Mr McCartney lived - for people with information to come forward.
In an interview with the BBC on Wednesday, Mr McCartney's sister Catherine said it was up to the republican movement to work out how to place the people who killed Mr McCartney before a court.
"People should not be asking us 'what do you want the IRA to do, what do you want Sinn Fein to do?'" she said.
"I do not believe the IRA who, remember are nearly 100 years old and in their history are probably one of the most notorious guerrilla warfare machines in the world, cannot resolve this issue."
She was speaking after the McCartney family issued its response to Tuesday's IRA statement, which said they had offered to shoot those involved in his killing.
They said it was only in court that justice would be done.
The family claimed up to 12 IRA members were involved in the cover-up following the murder.
"It was the cover-up which prevented those who murdered Robert from being brought to justice," they said in a statement on Wednesday.
They said the IRA could not give any reason why Robert was killed when the family met the IRA on 5 March.
The family, who will travel to Washington to meet President Bush next week, is now considering whether to open a campaign office.
Last week, police said that 10 people previously arrested over the killing stayed silent throughout questioning. All were released without charge.