Operation Gloucester was an investigation into improper evidentiary and disclosure practices in relation to the Victoria Police investigation of the murders of Sergeant Gary Silk and Senior Constable Rodney Miller.

The administration of justice requires that a statement made by a witness to police investigators is an accurate and full record of the witness's account and that the statement, if relevant, is disclosed in a criminal prosecution. A failure to comply with either of these requirements is likely to jeopardise that legal process. Without someone coming forward to say that these requirements have not been followed, non-compliance or related improper practices are unlikely to be detected.

Operation Gloucester identified a variety of improper practices by police officers with respect to witness statements which did not comply with proper evidentiary and disclosure practices. A number of these practices were used by some officers connected to the Lorimer Taskforce investigation and prosecution of Bandali Debs and Jason Roberts for the murders of Sergeant Gary Silk and Senior Constable Rodney Miller.

This report identifies improper practices which were consistently used by some officers within the Lorimer Taskforce and Homicide and Armed Robbery Squads. As none of these improper practices have ever been recorded or expressly identified by Victoria Police as practices that need to be corrected and which must not be followed, there is an appreciable risk that these practices, or variations of them, remain current. Indeed, most of these practices by their nature are hidden but the Independent Broad-based Anti-corruption Commission (IBAC) has detected current examples of a number of these practices. IBAC has made recommendations to address the risk of the occurrence of any of these practices in the future and to protect the integrity of investigations and the administration of justice.