Three people have been released without charge after being questioned in connection with the murder of Constable Stephen Carroll in Antrim in March last year.
Two men, aged 36 and 40, and a 37-year-old woman were arrested yesterday in the Craigavon area of Co Armagh.
The 48-year-old PSNI officer was shot dead by the Continuity IRA as he answered a call in Craigavon.
A teenager and a 38-year-old man have previously been remanded in custody charged with the murder.
