The family of murdered IRA spy Denis Donaldson have used the 10th anniversary of his death to appeal to Gardaí to "fully co-operate" with an investigation into his outing as an agent.
Mr Donaldson, 55, a senior Sinn Féin official and close colleague of party president Gerry Adams, was shot dead at an isolated cottage near Glenties in Co Donegal in April 2006.
The Belfast man 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.
The spy's family have lodged a complaint with the police complaints watchdog in the North, the Police Ombudsman, in regard to how his cover was blown.
They believe a journal he was writing in the months before his murder could hold vital information that could assist.
Gardaí are in possession of the diary and the family have accused them of refusing to grant the ombudsman access to it.
An inquest into the killing has yet to be heard, having been adjourned almost 20 times to facilitate gardaí requests for further time to pursue their criminal investigation into the shooting.
On the anniversary of the killing, the Donaldson family issued a statement through their lawyer Ciaran Shiels.
"Today marks 10 years since Denis was murdered," it stated.
"No-one has yet been held to account for either his exposure as an agent or his subsequent murder.
"An inquest has still not even been held, yet it has been adjourned on 18 occasions by the Coroner upon the application of An Garda Síochána.
"For the final time, the Donaldson family are calling upon An Garda Síochána to fully cooperate with the ongoing Police Ombudsman's investigation of Denis's exposure in the north by giving the investigators unfettered access to his private journal which was being written by him at the time of his murder.
"The Office of the Police Ombudsman for Northern Ireland is a fellow law enforcement agency and is following a definite line of inquiry in relation to the family's complaint.
"Despite repeated requests, they have been refused access to this document.
"The Donaldson family are appealing to all relevant state agencies, north and south, to finally remove any further obstructions to the truth and sincerely acknowledge the terrible damage they caused, or continue to cause, to the family by their actions and omissions.
"The onus is with them to remedy these wrongs."
The family is currently pursuing legal action against the Garda for alleged contravention of the Irish state's obligation to conduct a proper and timely investigation under the European Convention on Human Rights (ECHR).
A Garda spokesman said: "An Garda Síochána are pursuing a live active criminal investigation into the unlawful killing of Denis Donaldson at Clogheror, Doochary, Co Donegal on the 3rd /4th April 2006.
"A number of individuals have been arrested and questioned in relation to this investigation, as this is a live murder investigation, it is not appropriate to provide further details."