When Lorenzo Davis arrived at the corner of 53rd Street and Martin Luther King Jr. Drive on October 12, 2014, he found a familiar scene: A black man had been shot and killed by a Chicago police officer, and detectives were running the show. So Davis, an investigative supervisor with Chicago's Independent Police Review Authority (IPRA), started working outside the crime tape, looking for nearby surveillance cameras that may have captured the incident—the fatal police shooting of 25-year-old Ronald "Ronnie-man" Johnson.