FIANNA Fáil leader Michael Martin launched a scathing attack on Sinn Fein as he warned all political parties had to accept there be only one police force and one criminal justice system in Ireland.
Mr Martin - speaking as he conducted an intensive eve-of-polling canvass in his native Cork- bluntly warned that the 2007 killing of Paul Quinn and the campaign for justice by his parents had raised fundamental questions.
"Because there can only be one police force in Ireland, there can only be one criminal justice system - there can’t be alternative systems and this issue goes to the very heart of the whole Sinn Fein organisation in terms of how they operate and that needs to change," he said.
Mr Martin paid tribute to the courage and dignity shown by the Quinn family in their campaign for justice over the murder of their son.
The young man was savagely beaten to death by a gang of around 12 men after being lured to a remote farm shed.
It has been alleged he was killed because of a row he had with the son of a prominent IRA member.
"I met Breege Quinn about five years ago and have been in touch recently again – they have suffered an awful lot since the savage murder of their son," Mr Martin said.
"It has been so traumatic for Stephen and Breege and I think there is an obligation on Sinn Fein as a party and as a movement to apologise in a comprehensive way and withdraw any slur on his name."
Sinn Fein's Connor Murphy MLA publicly apologised this week for remarks in which he suggested Paul Quinn has been involved in criminality and smuggling along the border.
The issue became a major topic during the final leaders debate on RTE with Mary Lou McDonald warning the remarks by Mr Murphy were not acceptable.
The Sinn Fein leader subsequently had a 15 minute telephone conversation with the Quinn family about the matter.
Breege Quinn said she thanked Mary Lou McDonald for publicly saying her son was not a criminal.
However, Mr Martin said what the Quinn family had endured was totally unacceptable.
"The fact – that her son’s name was sullied in the way it was has left a deep hurt on the Quinn family and it’s extraordinary that it’s taken 13 years for an apology to emerge essentially because of Breege Quinn’s courage in consistently pursuing this," he said.
"She was against a big machine – she had to fight against a big operation and a big machine to have her voice heard and she’s done it over many many years."
"There should be a comprehensive withdrawal of any allegations but also people need to go to the PSNI and the Gardai and tell the police forces what exactly they know - who they spoke to at the time."
"How they got assurances around certain issues as to who was responsible and who was not? Who put this out in the first place in terms of the comments in relation to the late Paul Quinn?"
The Fianna Fáil leader stressed that the Gardai were the only police force in the Republic, there was only one criminal justice system and all parties had to be firm in their support of this and their absolute rejection of alternatives.