The family of double informer Denis Donaldson have said they will be taking legal action against the Gardai in the European Court in Strasbourg.
In a statement issued last night, the family claim An Garda Siochana failed to properly investigate his murder.
Donaldson, 56, was shot dead by gunmen in a rural cottage near Glenties on April 4, 2006.
The Real IRA claimed it was responsible.
In a statement issued through their solicitor Ciaran Shiels of Madden and Finucane they recalled it was exactly 10 years since Denis Donaldson was first exposed as an agent working for Special Branch and MI5.
The inquest into his murder near Glenties in 2006 was adjourned until next April for the 17th time yesterday.
The continuing adjournment was granted in Letterkenny by Coroner Dr Dennis McCauley after gardai told him they were following up “significant leads” and they were liaising and had full co-operation from a force outside the jurisdiction.
Three hours after the adjournment the family issued a statement that throughout the past decade gardai had refused to investigate any role played by serving or former members or agents of RUC or PSNI Special Branch or MI5 in Donaldson’s murder or his expose as an agent working for M15 and Special Branch.
They had refused to interview the Northern Ireland police handler known as “Lenny” who remained in contact with Donaldson after his exposure in December 2005.
The statement continued that gardai had refused to co-operate fully with the current Police Ombudsman's investigation in the north and had not discharged its statutory and moral duty to maintain regular and open liaison with the family about all aspects of this case.
The statement added: “A decade on, the Donaldson family’s patience is now exhausted.
“The Irish state must be held to account for its violation of our right to a Article 2 ECHR-compliant investigation, just as much as those responsible for causing Denis’ murder and the family’s ordeal.”
The family said they would be shortly consulting with legal advisors with a view to securing appropriate remedies at both domestic and European level.
They added: “In the meantime, a new complaint is being submitted to the Garda Siochana Ombudsman Commission about grievances highlighted on behalf of the Donaldson family.