Dangerous Minds

In a car outside a convenience store in Flint, Michigan, in late 2016, Kemo Parks handed his cousin Dequavion Harris a gun. Things happened quickly after that: Witnesses saw Harris “with his arm up and extended” toward a red truck. Shots rang out. The wounded driver sped off but crashed into a tree. EMTs rushed him to the hospital. He was dead on arrival.

Two weeks later, Harris was arrested following a car chase. He and Parks were charged with the murder of Darnyreouckeonu Jones-Dickerson, known to his friends as...