I was completing a decade-long study of the criminal court system in Chicago when I saw the autopsy diagram of Laquan McDonald. The Cook County medical examiner meticulously inventoried how all 16 bullets fired by a Chicago police officer, Jason Van Dyke, had entered and exited McDonald’s body on October 20, 2014. The Chicago Police Department’s official account of the incident claimed that McDonald had a knife and lunged at Van Dyke. Other officers were willing to vouch for that description—but the dashcam video showed otherwise. It took 13 months and a court order to expose the truth: McDonald was walking away from Van Dyke, and Van Dyke killed McDonald without provocation. In the video, you can see McDonald’s body smoking.