The Sinn Féin president, Gerry Adams, has warned the killer of Robert McCartney that self-preservation and selfishness would not prevail.
In a statement on the murder, Mr Adams said those who have sullied the republican cause would be made accountable for their actions.
Sinn Féin's justice spokesman Gerry Kelly has welcomed a suggestion that people with information about the Robert McCartney killing might go through the Police Ombudsman's office to give statements.
He said he met Nuala O'Loan and her staff on an ongoing basis and in the past had made statements to them himself.
Mr Kelly said he had confidence in the Ombudsman and the ability of her staff to take statements and to use them in the course of justice.
Earlier, one of Mr McCartney's sisters said if witnesses were unwilling to give statements directly to the police then the family would like them to give them to the Police Ombudsman.
Nuala O' Loan has confirmed her office is available to take witness statements as part of the murder inquiry.
The republican movement is under continuing pressure over Mr McCartney's murder.
Sinn Féin slammed over motion
Sinn Féin has been criticised for failing to support an SDLP motion put forward at Belfast City Council last night urging anyone with information to go to the police.
The motion was passed by 33 votes. Sinn Féin councillors abstained after failing to have an amendment passed.
The SDLP councillor who tabled the motion, Pat McCarthy, said he was disappointed but not surprised that Sinn Féin had not backed the call for co-operation with the police.
Sinn Féin has proposed an amendment to say that witnesses who do not trust the PSNI should be able to give information to a solicitor instead.
Ahern and Murphy in Dublin meeting
This afternoon, Minister for Foreign Affairs and the Northern Secretary agreed that if people who were prepared to go to a solicitor and give information in relation to the killing of Mr McCartney in Belfast and then were also prepared to go to court, this would be acceptable
Dermot Ahern and Paul Murphy were speaking after a meeting of the British/Irish Intergovernmental Conference in Dublin this morning. The agenda included the current impasse in the peace process and the killing of Mr McCartney.
Mr Ahern also said that the Government was absolutely certain that some of the money found in Cork came from the Northern Bank raid.
A 29-year-old man was released by police investigating the murder of Mr McCartney yesterday. The man had walked into a police station in the city earlier in the day. After being questioned for several hours he was freed without charge late last night.
He is said not to be one of the three men expelled from the IRA because of alleged involvement in the killing.