Why Busan Police conduct investigations in a way that inevitably leads to formal complaints

The Busan Police have no sense of human rights.
So I made another inquiry. But the officer told me that the person in question should take this opportunity to go to the police station's civil service center and file a formal complaint.
If you get sued, I won't settle with you. Just go serve your prison time.
Hey, cop. When you conduct an investigation, acting in a way that triggers a formal complaint is a serious violation of human rights.