A retired Canadian judge who is examining controversial killings is to begin looking at allegations of collusion between the IRA and Irish police.
Judge Cory is examining controversial murders
Peter Cory was appointed by the British and Irish Governments to investigate killings involving claims of collusion by the security forces with paramilitaries on both sides of the Irish border.
The former Canadian supreme court judge is determining the need for public inquiries into such high-profile cases as the murders of Catholic solicitors Rosemary Nelson and Pat Finucane.
On Monday, he begins work in Dublin examining the murders of Lord Justice Maurice and Lady Cecily Gibson, as well as the killings of two senior RUC officers, Harry Breen and Bob Buchanan.
It is the first government-backed investigation into allegations of gardai and IRA collusion to be held in the Republic of Ireland.
High-profile solicitor Rosemary Nelson was murdered
Chief Superintendent Harry Breen and Superintendent Bob Buchanan were allegedly set up for an IRA ambush in 1989 by a police officer in the Republic of Ireland.
The IRA opened fire on the officers near Jonesborough, after they had attended a security situation meeting with gardai in the border town of Dundalk.
Supt Buchanan died at the wheel of the car and the other officer was found dead on the roadside.
Mr Breen was the highest-ranking member of the Royal Ulster Constabulary to be killed by the IRA.
Lord Justice and Lady Gibson were killed by an IRA remote-controlled car bomb as they drove over the Irish border back into Northern Ireland after a holiday in April 1987.
As the judge's car reached the border, he stopped to shake hands with the garda security escort who had completed their part of the assignment. The couple had only a short drive to meet the RUC escort to Belfast.
Some unionists have alleged that the responsibility lay with an IRA mole within the gardai.
Irish Government sources have said that police and justice files going back to the time of the murders will be made available to Judge Cory.
Meanwhile, in Northern Ireland, Judge Cory has completed his review of the Rosemary Nelson case.
Catholic mother-of-three Rosemary Nelson died in a booby-trap car bomb near her home in Lurgan, County Armagh, on 15 March 1999.
There have been allegations of security force collusion in the killing because of Mrs Nelson's role as solicitor for the nationalist Garvaghy Road Residents' Coalition and other high-profile cases.
Justice Peter Cory said last Thursday that he aimed to finish his work by October.
In April, Mr Cory told the secretary of state he had finished his investigations into the cases of loyalist leader Billy Wright and Catholic man Robert Hamill.
The appointment of Judge Cory fulfilled a commitment made by the British and Irish Governments following the Weston Park talks in July 2001.