PC Carroll was shot dead by the Continuity IRA in Craigavon last March while answering a distress call. He was the first — and, to date, the only — PSNI officer to be murdered by paramilitaries.
Police said a man arrested in the Newtownabbey area yesterday was last night being questioned at Antrim police station.
PC Carroll (48) was married and came from Banbridge. He was murdered two days after the Real IRA shot dead two soldiers outside Massereene Barracks in Antrim.
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