A man in his 40s has been arrested by gardaí in connection with the murder of Denis Donaldson.
Mr Donaldson (55), a member of Sinn Féin, was shot dead at at Cloghercor, Doochary, Co Donegal, in April 2006 following his exposure in December 2005 as an MI5 agent.
The man is being held at Letterkenny Garda station under Section 30 of the Offences Against the State Act 1939 .
Gardaí have appaled to anyone with information to contact them at Letterkenny Garda station on 074-9167100 or the Garda Confidential Line at 1800-666111.