Incompetent

The Mayor of Baltimore has asked for a DOJ investigation of her police force. She sad in her statement that she believes there is a culture of excessive force, systemic behavior issues and a history of discrimination. If she believes this is the case, and she must or she would not seek outside investigators, why hasn't she fired the Police Commissioner and Police Chief? Better yet, since she is ultimately in charge, why hasn't  she resigned?  Harry Truman famously kept a sign on his desk claiming "the buck stops here".  Private companies fire heads of failing departments. Sports teams can the coach when performance is unacceptable. Democrat politicians just point fingers.