Denis Donaldson murder: Man arrested by Gardai investigating 2006 Donegal killing of IRA mole
Gardai investigating the Co Donegal murder of Denis Donaldson in April 2006 have arrested a man in his 40s.
He is currently detained at Letterkenny Garda Station under the provisions of Section 30 of the Offences Against the State Act 1939.
Last month, a 74-year-old man appeared in court in Dublin accused of withholding information about the murder.
Mr Donaldson (55), a 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.
The Belfast man had been living there since his exposure as an MI5 agent the previous year. In the early 2000s, Donaldson was appointed Sinn Fein's Northern Ireland Assembly group administrator in Parliament Buildings.
Dissident republican group the Real IRA claimed responsibility for the murder, but the circumstances surrounding Mr Donaldson's outing and subsequent murder have 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.
The delays have been a source of anger for Mr Donaldson's relatives. They have launched a legal action against the Irish state as a consequence.
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.
Gardai are appealing to any persons who may have information in relation to this investigation to contact them at the Incident Room at Letterkenny Garda Station at 074 9167100, the Garda Confidential Line at 1800 666111 or any Garda Station.
Belfast Telegraph Digital