Investigations into sex allegations made by Rotorua woman Louise Nicholas and other allegations involving officers cost police more than $4.5 million, it has been revealed.
National crime manager Detective Superintendent Win Van der Velde says Operation Austin involved 23 alleged victims of 11 police officers.
Almost 100,000 police hours (99,527) were spent on the cases between 2004 and 2006. Six offenders were successfully prosecuted.
Mr Van der Velde says police do not normally record costs of a particular investigation, but this case was set up with its own cost centre.
He says police decided to release the figures in response to a number of requests.
Clint Rickards, Brad Shipton and Bob Schollum were found not guilty of allegations made by Mrs Nicholas, although Shipton and Schollum were jailed for another rape.
John Dewar was jailed last year for attempting to obstruct or defeat the course of justice while he was head of the Rotorua CIB.