Aaron Shannon in his Halloween costume taken by his grandfather shortly before he was shot in the back of the head in the backyard of his South Los Angeles home.(Family photo)

Aaron Shannon in his Halloween costume taken by his grandfather shortly before he was shot in the back of the head in the backyard of his South Los Angeles home.(Family photo)

Until this homicide, recent news about gang violence in Los Angeles had been positive. Citywide, gang-related crime has been falling, and where the Summer Night Lights program was active, the reductions were particularly dramatic, with a 57% decrease in homicides. That program kept parks open after dark from July 4 to Labor Day; an audit found that residents made 710,000 visits to the program's 24 sites and that free meals were served to 10,929 people.

One crucial component to combating gangs is changing the culture in the neighborhoods where they operate. That includes building a trusting relationship between residents and the police and encouraging a willingness to cooperate with investigations and prosecutions. The mayor's gang czar, Guillermo Cespedes, says Summer Night Lights' real success is not in statistics but in community buy-in. In Aaron's case, the community rallied against the perpetrators, and even gang members cooperated with the investigation, police said, a sign of hope in an otherwise tragic situation.

The best programs cannot stop every random act of viciousness, and public safety is not only about catching criminals— it is about stitching together neighborhoods that will not tolerate gang warfare. That's the work that continues.,,