The Northern Ireland Police Ombudsman has opened a new investigation into the murder of IRA spy Denis Donaldson.
The office of Dr Michael Maguire confirmed a new inquiry is under way into the police's handling of the case.
Mr Donaldson, 55, a senior Sinn Fein official and close colleague of party president Gerry Adams, was shot dead at an isolated cottage in Co Donegal in April 2006. He had been living there since his exposure as an MI5 agent the previous year.
The Real IRA claimed responsibility for the murder three years later but the circumstances surrounding Mr Donaldson's outing and subsequent assassination have been shrouded in mystery.
Three years ago the then Ombudsman Al Hutchinson said there had been no police misconduct and declared closed his inquiry into the police handling of the affair.
It is understood Dr Maguire ordered his officers to make new inquiries following claims Mr Donaldson was keeping a journal of his time in exile and had connections with a Special Branch officer.
Mr Donaldson, from West Belfast, was living alone in a famine cottage near Glenties in Co Donegal when gunmen burst in and shot him. The inquest into his death has yet to take place. Several people were arrested for questioning but nobody has been charged with murder.