Tensions between Watts residents and the police ran high. While the vast majority of Watts residents in 1965 were black, only 4 percent of the sworn personnel of the Los Angeles Police Department and 6 percent of the Los Angeles County Sheriff’s Department were black. Police Chief William Parker used analyses of crime data to develop and justify a policy that explicitly targeted Watts and other black neighborhoods for heavy police coverage, including intrusive techniques such as routine frisking of people on the street. “I don’t think you can throw the genes out of the question when you discuss the behavior patterns of people,” Parker wrote in 1957. [...]