Three people have been arrested in connection with the murder of PSNI constable Stephen Carroll, who was killed by the Continuity IRA in the North in March 2009.
The police officer from Banbridge, Co Down, was shot in the back of the head as he sat in the back seat of a police car while providing backup for colleagues checking out a report of vandalism in the Lismore Manor area of Craigavon.
He was murdered just 48 hours after the Real IRA shot dead two British soldiers in the Massereene British army base in Antrim.
The Police Service of Northern Ireland (PSNI) said it had arrested a 40-year-old man in Lurgan and a 36-year-old man and 37-year-old woman in Craigavon earlier today.
A 37-year-old man and a teenager were previously arrested over the constable's murder at the end of March 2009.