A 45-year-old man arrested in Belfast on suspicion of murder has been released without charge.
The man had been detained on the Grosvenor Road in the west of the city shortly before 1430 BST on Friday under the Terrorism Act 2000.
The arrest was in connection with the killing of Reserve Police Constable Colin Carson in Cookstown, County Tyrone in 1983.
He was released on Saturday after questioning at Antrim police station.
The police say a file on the matter will be sent to the director of public prosecutions.