The late Denis Donaldson
Two men are being questioned at Letterkenny garda station in connection with the murder of Denis Donaldson in Donegal in 2006.
One of the men arrested is Derry and Strabane independent
It is understood
Another man aged in his 30s is also being held.
The men are being detained under Section 30 of the Offences Against the State Act.
He was murdered just four months after being exposed as a British agent.