The Gibsons died in a massive IRA explosion at Killeen Border crossing as their car progressed along the main Dublin to Belfast road in April 1987.
They were returning to Northern Ireland from holiday and were travelling unprotected, having left their Garda escort but not met their RUC escort.
There were concerns that the IRA had acted on intelligence that may have come from a sympathiser within the Garda. For this reason Judge Cory's report is being handed to the Taoiseach even though the blast happened in south Armagh.
Billy Wright, known as King Rat
Billy Wright was the leader of the notorious Loyalist Volunteer Force which was responsible for sectarian assassinations in north Armagh. He was shot dead by the INLA in the Maze jail where he was a prisoner, on December 27th, 1997. INLA prisoners were convicted of the murder, but there are lingering concerns, voiced principally by Wright's father, that officials aided the gunmen.
Wright was shot as he was being transferred by prison officers and questions persist about the monitoring of the transfer.
A TV camera was found not to be working.
Bob Buchanan and Harry Breen
These were two senior RUC officers shot by the IRA as they crossed the Border near Jonesboro in south Armagh in March 1989.
The attack followed a meeting they had attended with senior counter-terrorism gardaí in Dundalk.
Their murders prompted a chorus of concern from unionists that the IRA was in possession of sensitive intelligence about the movements of senior RUC officers. Following the Gibson murders, there were further allegations that a Garda mole was passing such information.
Pat Finucane
Perhaps the most controversial murder of the Troubles, Mr Finucane was a high profile and respected lawyer.
He was shot many times in front of his family as they prepared Sunday dinner in February 1989.
His murder prompted the holding of investigations by Sir John Stevens, the commissioner of London's Metropolitan Police and now Britain's most senior officer. He has found there was British state collusion with loyalist paramilitaries.
Sir John's investigation, which is ongoing after 14 years, is the longest in British history. However, despite the handing of an interim report on the killing to the PSNI, only 19 pages of findings have been released by Sir John. Ken Barratt, a UDA figure, is facing charges in connection with the killing.
Rosemary Nelson
Ms Nelson, a Lurgan-based solicitor, died when a booby-trap bomb exploded under her car outside her home in March 1999. The murder was claimed by the Red Hand Defenders, a cover name used by the LVF. Ms Nelson had acted as legal representative for the Garvaghy Road residents in the Drumcree dispute.
She said she had received death threats and had been assaulted by police. But there were allegations that the delay in investigating the death threats may have proven fatal.
Robert Hamill
Mr Hamill, a Catholic, died nearly two weeks after he was beaten by a loyalist gang in Portadown, Co Armagh. He died in May 1997. There were claims that the RUC, sitting in a vehicle, observed the attack but failed to intervene.
There is evidence of serious faults, and worse, in how some police officers conducted themselves before, during and after his assault.
The policing ombudsman, Ms Nuala O'Loan, was also called in to investigate.
Compiled by Dan Keenan