Garda Síochána hold man in his 40s for questioning in Co Donegal over killing in April 2006
Irish detectives have arrested a man in his 40s in connection with the murder of Denis Donaldson, an MI5 spy who operated at the heart of the IRA and Sinn Féin.
The suspect was detained at Cloghercor in Doochary, Co Donegal, on Thursday.
The Garda Síochána are questioning him at Letterkenny garda station.