Brian Stack's family have received an apology from the Garda Commissioner over "failings and shortcomings", which had a detrimental impact on the investigation into his murder.
They've held a 90 minute meeting with Drew Harris, where they say they were told Gardai will submit a file to the DPP but do not believe there's enough evidence to bring a prosecution.
Mr. Stack - who was a prison officer at Portlaoise Prison - died 18 months after being shot by the IRA in 1983.
His family is now urging the Minister for Justice to appoint an independent police expert to examine the case.
Brian Stack's son, Austin says they appreciate the Garda apology: "it's actually quite significant that the Gardai are at this stage admitting that there were errors, admitting to the family that things that should of been done weren't done and I think its right and proper that the Commissioner would acknowledge that and I thank him for doing so."