A 70-year-old man has been arrested in Co Donegal tonight in connection with the murder of Denis Donaldson.
The man is being detained at Letterkenny Garda Station on suspicion of withholding information. He can be held for three days.
Former Sinn Féin official Mr Donaldson, who had admitted being a British agent for more than 20 years, was shot dead just outside the town of Glenties, Co Donegal, in 2006.
Mr Donaldson, who was the former head of Sinn Féin's office at Stormont, had been living in Co Donegal since he admitted he had spied for the British.