The SDLP has called for an independent inquiry into the killing of a Catholic man, Mr Robert Hamill, following a decision not to prosecute four RUC officers who were on duty the day the victim died.
It is understood his family are now considering pursuing a private prosecution. Mr Hamill (25) and a cousin were set upon by a group of loyalists as they walked through Portadown, Co Armagh, after a night out in April 1997. The father of three suffered serious head injuries and died in hospital the following month.
His family later lodged an official complaint about the incident. They claimed that RUC officers on duty witnessed the attack but failed to intervene. One man, Marc Hobson, was later jailed for four years for causing an affray on the night of the incident.
The trial judge, Lord Justice McCollum, said he was unable to resolve the question whether police officers had stayed in their Land Rover during the attack. He said the only issue that might reflect on the officers, and about which no evidence existed, was whether they had failed to anticipate the attack.
The Director of Public Prosecutions considered evidence from the trial and in particular Lord Justice McCollum's comments. It is understood the DPP is maintaining that independent legal advice indicated there was no prospect of a successful prosecution of the police officers.
An internal RUC investigation into the incident will be supervised by the Independent Commission for Police Complaints. However, SDLP Assembly member Mr Alex Attwood has demanded an independent inquiry.
Sinn Fein Assembly member Ms Dara O'Hagan said the Hamill family were upset by the decision. "They are shell-shocked but not surprised. Once again the system has let them down."
A spokesman for the Pat Finucane Centre in Derry said it was unbelievable that the DPP had taken the decision "because there was no reasonable prospect of convicting any of the officers". He said none of the four RUC officers had even been suspended from duty.
An RUC spokesman said: "It must never be forgotten that the brutal murder of Mr Hamill is first and foremost a human tragedy which has caused immense grief to the immediate relatives and wider family circle, but also for the police officers concerned.
"The DPP's decision represents only one more stage - there has already been one criminal trial and there remains the inquest. There are also decisions to be taken on outstanding disciplinary matters ..."
The Taoiseach, Mr Ahern, was last night urged to intervene in the Hamill case.
Fine Gael said the Hamill affair raised matters of serious concern which Mr Ahern should relay to the British Prime Minister, Mr Tony Blair. Mr Charles Flanagan, the party's Northern Ireland spokesman, said: "It is vital in the interest of justice and fair play that the full circumstances surrounding the death of Robert Hamill should be established beyond doubt and in a transparent way that will command the confidence of the entire community."