A report into the 1976 murder of Seamus Ludlow has not been able to clearly establish who killed him.
The 100-page reoort by Justice Henry Barron published by the Oireachtas Committee on Justice, Equality, Defence and Women's Rights, said the Dundalk forestry worker's death was a random sectarian killing of an innocent Catholic by loyalist extremists.
The document also states that it was "most probable" that the Garda decision not to pursue information offered by the RUC in the Ludlow inquiry was made by then Deputy Commissioner Laurence Wren.
"Before doing so, it is likely that he would have discussed the matter with other senior Gardaí and possibly senior officials from the Department of Justice. However, the absence of files means that this cannot be confirmed."
Former Garda Commissioner Patrick Byrne was asked for his views on the failure to question four suspects in the killing in 1979. In a letter to the inquiry, Mr Byrne placed blame with the Garda Síochána for failure to pursue information on Mr Ludlow's killing.
A sub-group of the justice committee will hold public hearings in mid-January on the report.
The report, released under full parliamentary privilege, states that Mr Ludlow was picked up in a car in May 1976 by four men.
Mr Justice Barron said he had no evidence that Mr Ludlow had any republican sympathies which might have led to him being targeted by loyalist subversives.
Fianna Fáil TD Sean Ardagh, chairman of the committee and the newly established sub-committee, refused to comment on the report's content or pre-empt the findings of the sub-committee.
Mr Ardagh said: "Committee members only received this report at 11.30am today and have not had a chance to consider it fully."
Mr Justice Barron said his job was made more difficult as documents were lost, destroyed or misplaced and key witnesses were ill, dead or unable to remember important events.
Additional reporting: PA