Sergio Williams was 18 when he was killed on December 3, 2008, in Chicago after a high school basketball game. The shooting occurred on a street near Dunbar High School following a flare-up of tensions there; multiple gunshots were reported during the confrontation. Witnesses identified several possible suspects and repeatedly named three individuals—Kwan, Mike, and Manno—as persons of interest, and some witnesses mentioned distinctive physical features such as severe acne for one possible suspect.

Accounts from witnesses varied and at times conflicted, and that lack of cohesion complicated efforts to build a strong prosecution case. The killing took place during a period of elevated youth violence in Chicago in which confrontations could rapidly turn deadly and witness cooperation was often limited by fear or chaos at the scene. Anyone who was at Dunbar High School or on the nearby street that night, or who has information about the people named, is asked to come forward.