Seven people, including a reserve RUC officer, who were arrested as part of an investigation into the death of Mr Robert Hamill in Portadown, Co Armagh, four years ago, have been released on police bail.
The five men and two women were detained on Tuesday morning but were freed later that night. The arrests were carried out on the orders of the Northern Ireland Police Ombudsman, Ms Nuala O'Loan.
Mr Hamill (25) was kicked and beaten to death by a group of loyalists as he returned home with friends in April 1997. RUC officers have been accused of not intervening when witnessing the attack from their LandRover. The RUC claimed its officers were overwhelmed.
The DUP criticised Ms O'Loan for publicly releasing details of the arrests. Mr Ian Paisley jnr said the individuals detained had all been released and claimed her actions "did nothing to help solve this terrible crime".
However, a spokesman for Ms O'Loan said: "When she took office, the ombudsman gave a commitment to be as open and transparent as possible. What we did was inform the public of what happened - no more than that."