David Black was killed by suspected dissident republicans in a high-speed shooting on a motorway as he drove to his prison workplace.
He was the first prison officer killed by paramilitaries in Northern Ireland in 20 years and was from Cookstown in Co Tyrone in Mid-Ulster.
He was enroute to Maghaberry high-security jail in Co Antrim in November 2012 when he was targeted.
Gunmen travelling in a stolen car fired on the victim's Audi near a junction leading to Portadown, Co Armagh, as he was on his way to Maghaberry. The car careered off the road and into a ditch.
Mr Black, who had more than 30 years' service, was the first prison officer to die at the hands of paramilitaries since 1993.
His family branded his killers "cowards" during his Presbyterian funeral service.
Cousin Jim Slaine told mourners he left school at 16 and worked in a bacon factory before joining the prison service. Shortly after that he met his wife Yvonne.
Mr Black had described his daughter Kyra, aged 17 when he died, as his little princess and wanted the best for his son. He took over a family farm and had rental properties. He put his family first.
At the time his son Kyle said: "They can take daddy from us... they can deprive mummy of a loving husband, but they can never take away the love that we have in our hearts and the memories that we will all cherish for the rest of our lives."
The killing prompted united political condemnation from Sinn Fein's Martin McGuinness and the DUP's Peter Robinson, then Irish Taoiseach Enda Kenny and members of the US administration.
Dissident republicans opposed to the peace process in Northern Ireland have killed police, soldiers and prison officers.
Police believe the threat posed to members of the security forces in Northern Ireland remains severe.
Mr Black's killing was claimed by a group calling itself the New IRA.
It is a dissident group which opposes Sinn Fein and its peace strategy.
It is said to consist of individuals from Omagh, Coalisland and the Toomebridge and Ballyronan areas along the shore of Lough Neagh, and in counties Monaghan and Louth in the Republic of Ireland, with their actions directed from Belfast.