Minister for Justice Michael McDowell has cast doubt on the possibility setting up of a public tribunal of inquiry into the 1976 murder of Séamus Ludlow.
At the Oireachtas justice committee on the Barron report into the Co Louth man's murder, Mr McDowell said there were serious constitutional issues about setting up an inquiry to effectively mimic a criminal trial 30 years after the crime.
Journalist Ed Moloney, who in 1998 wrote about the murder in the Sunday Tribune and interviewed a suspect, said he disagreed with Mr McDowell and called for a public inquiry to make recompense to the family.
Solicitor Francis Keenan, who attended with Mr Moloney, said an unnamed client would be willing to give evidence at an independent judicial inquiry.
Mr Ludlow (47), a single man and forestry worker, was shot dead on May 2nd, 1976, at Thistle Cross, Dundalk, Co Louth, as he went home after a night out. The Barron report said he had no connections with any subversive organisation. No one has ever been charged with the murder.
The report states that the RUC told the Garda in 1979 it believed four named loyalists were involved in Mr Ludlow's killing but the information was not pursued by gardaí. The Minister said serious constitutional difficulties would surround a public inquiry to establish whether someone did or did not commit a crime 10, 20, 30 years earlier.
The committee might conclude that there was an unsatisfactory investigation and that the DPP in Northern Ireland was right in 1999 to say there was insufficient evidence to charge the four suspects with which the DPP in the State concurred.
"But it still doesn't follow that it is lawful for the Irish State to establish an inquiry to effectively mimic a criminal trial," he said.
Mr Moloney said the family had been treated abominably.
"A full public inquiry could only begin to make recompense. I do not agree with the Minister. It flies in the face of his own Government policy to support the Bloody Sunday inquiry and that was 30 years later. The Government supported that, so why not this?" .
Mr Moloney said it was not the job of a public inquiry to try the suspects but to inquire into whether the State fell down in its duty in investigating the murder.
The question had to be asked, no matter how awkward or embarrassing. Was one of the killers a loyalist paramilitary, an agent of British intelligence and was it covered up by the RUC and gardaí, he asked.
He interviewed one of the four suspects. He said he was not at liberty to describe details but he would tell a public inquiry.
Mr Keenan said: "I have received instructions from another client, who for obvious reasons I cannot name, that in the event of an independent judicial inquiry and he is satisfied with the guarantees offered to him, would be willing to appear and give evidence."
Asked if he would give the name privately, he refused: "I don't think it would take the wisdom of Solomon to work it out from the range of persons."