Published Wednesday, 19 December 2012
David Black died in an ambush on the M1. (© PA)
Police said the 36-year-old has been charged under Section 5 of the Terrorism Act.
He is due to appear before court in Lisburn on Thursday.
The man was detained in Co Tyrone on Tuesday.
A 44-year-old man and 31-year-old woman are also in police custody in Dublin.
A statement from the PSNI said: "The PSNI and Gardaí continue to liaise in this investigation."
Mr Black was shot dead on the M1 motorway near Lurgan in Co Armagh last month as he drove to work at Maghaberry Prison.
© UTV News