Two men are now being questioned in connection with the murder of Republican informer Denis Donaldson.
Mr Donaldson, who admitted being a British agent for more than 20 years, was shot dead near Glenties, Co Donegal in 2006.
A 70-year-old man – detained in Donegal yesterday – is being questioned at Letterkenny Garda Station under section 30 of the Offences Against the State Act.
A second man was arrested last night in connection with the 2006 attack in Glenties.
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