Retired Canadian judge Peter Cory has begun work on his final case in six of the most controversial murders of the Troubles.
The 77-year-old judge was appointed by the British and Irish governments to investigate the killings involving allegations of security force collusion on both sides of the border following the Weston Park negotiations in 2001.
It is understood Justice Cory, who has been working full time on the cases since last August, hopes to have completed his examination by October.
Both governments have said they will publish the reports and establish public inquiries if they are recommended.
The judge is in London reviewing documents relating to the murders of RUC officers Chief Superintendent Harry Breen and Superintendent Bob Buchanan.
It has been alleged they were set up for an IRA ambush in 1989 by a former Garda officer.
The men gunned down by the IRA on Edenappa Road, near Jonesborough in south Armagh after attending a meeting at a Garda station in Dundalk.
Judge Cory's work is the first government-backed investigation into allegations of gardai and IRA collusion to be held in the Republic.
The judge has already finished five reports on the deaths of solicitors Pat Finucane and Rosemary Nelson, Lord Justice and Lady Gibson and LVF leader Billy Wright and Portadown man Robert Hamill.
