He has been arrested on suspicion of bribery and procuring misconduct in public office and has been taken to the Serious Crime Suite at Antrim police station for questioning.
Six men arrested in Northern Ireland and England on Tuesday as part of the investigation remain in custody.
One of those being quizzed is former PSNI Assistant Chief Constable Duncan McCausland.
Another suspect is a serving a PSNI officer.
Police enquiries are continuing and further arrests are expected as the investigation widens.