A man in his 70s is due before court in Ireland in relation to the investigation into the murder of IRA spy Denis Donaldson.
The 55-year-old senior Sinn Fein official and close colleague of party president Gerry Adams was shot dead at an isolated cottage near Glenties in Co Donegal in April 2006.
A Garda spokesman confirmed the man was to appear at the non-jury Special Criminal Court in Dublin.
It is understood he is charged over withholding information.
He was one of two men arrested on Tuesday in Donegal.
The Garda spokesman said the second man, aged in his 40s, was released without charge and a file would be prepared for the Director of Public Prosecutions.
Mr Donaldson had been living in a remote area of Donegal following his exposure as an MI5 agent a year before his death.
Dissident republican group the Real IRA claimed responsibility for the murder in 2008, but the circumstances surrounding Mr Donaldson’s outing as a British agent and subsequent assassination have long been shrouded in mystery.
A long-delayed inquest into the shooting has been adjourned almost 20 times.
Gardai have repeatedly urged the coroner to postpone the probe, citing concerns it might compromise their criminal investigation.
In 2014, the Garda made a mutual assistance request to a police force outside the Irish Republic in a bid to gain what it described as potentially “significant” evidential material.
That material was secured in March this year.