The Dáil has heard claims that members, or past members, of the IRA were involved in the murder of Paul Quinn in Monaghan last October.
However, Minister for Justice Brian Lenihan said gardaí have no information to suggest that the murder of Mr Quinn was authorised or carried out on behalf of the Provisional IRA.
Brian Lenihan was speaking at the start of statements in the Dáil on the murder of Mr Quinn, who was lured from his home in Cullyhanna in south Armagh to a cattle shed in Monaghan, where he was beaten to death by a gang of masked men.
Minister Lenihan said the police investigation was live and ongoing, and that gardaí and the PSNI were determined that the border will not be a barrier to the investigation.
The Minister said: 'The obvious planned nature of the assault makes it all the more reprehensible. I fully support [the Quinn family] in their quest to see those who perpetrated this savage act brought to justice.'
Fine Gael leader Enda Kenny said this murder was now a litmus test for the peace process, because there is no peace process if there is bad justice.
He said reports indicate that people who are or were members of the IRA carried out the murder.
Deputy Kenny said the IRA's structure creates the fear, intimidation and bullying that is preventing witnesses coming forward.
Labour's Liz McManus said she had little doubt that members of the Provisional IRA carried out the murder, but she did not know if it was sanctioned by the organisation.
She said there was now a choice for the members of the Provisional movement - did they stand with the murderers of Paul Quinn, or with his family.
Sinn Féin's Caoimghín Ó Caoláin condemned what he called a 'despicable act of brutality and murder, carried out by people who deserve only the contempt of society'.
Speaking after the Leinster House statements, Paul Quinn's father, Stephen, said Sinn Féin has not yet done enough to bring his killers to justice.
He urged Sinn Féin to completely lift any allegation of criminality against his son, and to help bring the murderers to justice.
Mr Quinn said Sinn Féin seemed to know who had not carried out the murder, so they must know who did do it.
He said the murder could not have been carried out by ordinary people, it was highly organised and must have had some structure behind it.
