A Material Witness

S1 E9: In responding to a call Atwater (LaRoyce Hawkins) and Burgess (Marina Squerciati) discover a gunshot victim and the only witness is Lexi Olinsky (guest star Alina Taber). The shooting is tied to a Latin gang. To protect Olinsky's (Elias Koteas) daughter, Voight (Jason Beghe) takes the case from the Gang Unit. Ruzek (Patrick Flueger) pulls up Burgess to help with an undercover mission that he hopes will help solve the case.