The family of a County Louth man killed in 1976 have called for a independent, public inquiry into his murder.
Mr Justice Barron criticised the 1976 murder investigation
Four loyalists suspected of killing Seamus Ludlow have been named in a Dublin judicial report.
The report's author, Mr Justice Barron, criticised the Garda investigation into the murder near Dundalk in May 1976.
He said gardai failed to question four NI suspects named in the report because the RUC might have demanded reciprocal rights in the Irish Republic.
Seamus Ludlow's family have claimed collusion on both sides of the border.
They have maintained there was a cover-up following the murder.
"It basically copperfastens what the family have been saying for years," Mr Ludlow's nephew Jimmy Sharkey said.
"The Garda knew all along who the killers of Seamus were and didn't do anything about it."
Mr Sharkey said gardai had started a sort of "smear campaign" against the family, claiming Seamus Ludlow had been an IRA informer and that the IRA had been involved in his murder.
"They actually went as far as telling Seamus' brother Kevin that it was a member of the family who had him killed," he said.
Mr Sharkey said the family now wanted an inquiry into the murder.
"The bottom line for us is an independent, public inquiry."
Last month, an inquest into the 47-year-old forestry worker's killing was told that in 1998, the RUC arrested and questioned four men.
Two of them independently gave evidence of how and where the murder was committed.
However, the Director of Public Prosecutions in Northern Ireland decided not to press charges.
The inquest was also told that in 1979, Irish police had the names and addresses of the same four men but Garda Headquarters did not allow the investigating officers to proceed.
Mr Justice Barron, a retired judge, said it was important to view these matters in the context that the period between 1976-1980 was "one of huge turmoil".
"Deep divisions and distrust existed, not only between the nationalist and unionist communities in Northern Ireland, but also between the governments of the United Kingdom and this (Irish) state," he said.