David Hamilton was beaten to death at his flat on the Ballybeen estate in Dundonald in November 2004.
The suspect was detained in Bangor by detectives from the PSNI's serious crime branch.
Mr Hamilton, 40, suffered multiple head injuries in the attack in his flat in Gleneagles Gardens.
Three men have already been convicted of his murder.
The arrested man is being questioned by officers at Bangor police station.
The man was later released pending the submission of a police report to the Public Prosecution Service.
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