There is "no mystery" about who was involved in the murder of Belfast man, Mr Robert McCartney, but the issue is to get people to co-operate with the PSNI, the Taoiseach has told the Dáil.
Mr Ahern also said that "there are people who can resolve the McCartney murder very quickly.
"Not only were these people present at the scene of the crime - this is known - but they also had the audacity to go back to the scene of the crime to sweep the place clean. It is bad enough killing people but to do that is horrendous."
The names were well known and were "freely spoken about in the Short Strand.
"I will not mention names but I have talked to several people who told me who was involved. It is well known. There is no mystery about it," Mr Ahern added.
During Opposition leaders' questions which focused on the peace process, he said that "dealing properly with the PSNI" was the only way to stop the "bully boys and thugs".
He was speaking in advance of a meeting between the Minister for Foreign Affairs, Mr Ahern, and the sisters and partner of Mr McCartney who was killed when he was stabbed in a row in a pub in the Short Strand area of Belfast, three weeks ago.
Fine Gael leader, Mr Enda Kenny, who heard the family interviewed on RTÉ Radio yesterday morning said that their fundamental point was that comments made by the leadership of Sinn Féin, principally the president, Mr Gerry Adams, "have no impact on the ground because that is the way they are".
Mr Kenny said that Sinn Féin "should at least dissociate itself from the killers of Robert McCartney, for example by expelling them from the republican movement".
If Sinn Féin wanted to "make the hard decisions" and dissociate itself from criminality "they could in the first instance speak to the IRA person in Belfast of republican leanings who issued the instruction to murder Robert McCartney, who was an innocent man".
Socialist Party leader, Mr Joe Higgins, said that "we must categorise as vacuous doublespeak the words about Robert McCartney's murder by the leaders of republicanism". He said the reality "behind the seemingly sincere words of republican leaders is the screaming silence of the 50 witnesses who are terrified to speak out, to bring the murderers to justice, because of the intimidation coming from the very associates of those leaders, who say they want justice".
He said that Mr Adams "has a problem going to the police. Does he have a problem in going to the Short Strand unit of the provisional IRA - call it the local SS unit for short - and demanding that it present itself to justice".
He said the McCartney family had reported that Sinn Féin MLA Mr Gerry Kelly refused to call a public meeting in the Short Strand.
Labour leader, Mr Pat Rabbitte, said the family had described "the gruesome, Mafia-style killing and the swagger of those bully boys who dominate working-class nationalist communities through terror, fear and punishment beatings".
He said it was "important that this issue be clarified once and for all.
"We should regard this as an opportunity to do so rather than as a betrayal of the peace process".
