The Rosemary Nelson Inquiry was set up by former Northern secretary Paul Murphy in 2004 in response to recommendations by former Canadian supreme court judge Peter Corey.
Following political talks hosted by the British and Irish governments at Weston Park, England, in 2001 he was requested to investigate a series of disputed murders, two in the Republic and four in Northern Ireland - in which state collusion was alleged or suspected.
In addition to the Nelson case, inquiries were ordered into the killing of Robert Hamill, kicked to death in Portadown, Co Armagh and into the murders of loyalist leader Billy Wright in the Maze Prison and of solicitor Pat Finucane.
He also called for investigations into the murders of RUC officers Harry Breen and Bob Buchanan who were shot as they returned from meeting Garda contacts in Dundalk, Co Louth.
Sir Michael Morland, a retired judge of the high court of England and Wales, is the chairman of the inquiry.
Those joining him are: Dame Valerie Strachan, former chairwoman of the Board of Customs and Excise, Sir Anthony Burden, former chief constable of South Wales Police and a former president of the Association of Chief Police Officers.