SIU, or Special Investigations Unit, is a civilian agency in Canada that investigates incidents involving police officers. Its primary role is to ensure accountability and transparency in law enforcement by examining cases where serious injury or death occurs during police interactions. The SIU operates independently from the police to maintain impartiality. It gathers evidence, interviews witnesses, and determines whether officers acted within the law. If necessary, the SIU can recommend charges against officers involved in misconduct, helping to uphold public trust in the justice system.