Taoiseach Micheál Martin will this afternoon deliver a formal State apology to the family of murdered prison officer Brian Stack over failings in Garda investigations into his death.

Mr. Stack, who was Chief Prison Officer at Portlaoise Prison, was shot in the neck after leaving a boxing match at the National Stadium in Dublin in March 1983.

He was left paralysed and died from his injuries 18 months later, in September 1984.

The Provisional IRA later admitted responsibility for the killing, but no one has ever been brought to justice.

Mr. Martin is due to address the Dáil this afternoon, with Minister for Justice Jim O’Callaghan also expected to speak.

The Stack family will attend the proceedings after holding a private meeting with the Taoiseach and Justice Minister at Government Buildings.

Brian’s son Austin Stack said the apology would bring comfort to the family more than four decades after his father’s death.

He has previously criticised the initial Garda investigation, saying an obvious line of inquiry linked to his father’s role at Portlaoise Prison was not properly pursued.

‘At the time that wasn’t investigated and we believe from the get-go, it was the only motive that could’ve been,’ he said.

‘The Gardaí never came down to Portlaoise and interviewed prison staff, prisoners, colleagues of my dad, some of the community organisations he was in, they never interviewed family members, so it was fundamentally flawed from the get-go.’

There were three separate Garda investigations into Mr. Stack’s death.

In 2019, the family received an apology from then Garda Commissioner Drew Harris over failings in the investigation.

In a statement issued in 2018, An Garda Síochána said investigators were satisfied they had been provided with all relevant information from within the organisation and were pursuing all possible lines of inquiry.

The force also said it remained in regular contact with the Stack family and was determined to bring the investigation to a successful conclusion.

The formal State apology is due to be delivered in the Dáil this afternoon.