Labour leader Pat Rabbitte has accused Sinn Féin public representatives of refusing to intervene in a dispute between two families in Dublin's south inner city which claimed the life of Joseph Rafferty who was gunned down on the Ongar estate in west Dublin in April.
Mr Rabbitte led a Labour delegation which met members of Mr Rafferty's family in Leinster House yesterday.
Having listened to Mr Rafferty's sister Esther Uzell and the dead man's brother-in-law Bart Little, he was satisfied that the man who killed Mr Rafferty was a member of the IRA.
There were "striking similarities" between Mr Rafferty's murder and the killing of Robert McCartney by the IRA outside a Belfast bar in January.
"Sinn Féin representatives refused to intervene to save a life prior to the murder and the least they can now do is assist the family and gardaí in bringing the murderer to justice."
He urged Sinn Féin to assist Mr Rafferty's family, who have started a "Justice for Joe" public campaign.
Ms Uzell has said she told Cllr Daithi Doolan (SF) about the threats against her brother a number of times last year and earlier this year. She said Cllr Doolan assured her that the people issuing the threats had been spoken to and that the matter had been resolved.
However, Cllr Doolan has said that at no time was he informed of any threat against the life of Mr Rafferty being made by the man who allegedly killed him.
He has said he was informed by Ms Uzell that brothers from the south inner city, where Ms Uzell and her brother are originally from, had threatened Mr Rafferty. He was asked to find out if these men were in the IRA.
He says he did this and relayed to the family that the men were not in the IRA.
The man who allegedly shot Mr Rafferty is in a relationship with the mother of the brothers. Gardaí have confirmed to the The Irish Times that he was in the IRA and still has strong links to that organisation. Sinn Féin's leader on the council, Cllr Christy Burke, has said he is satisfied the killer is not a member of the republican movement.