CSI: NY: Season 7, Episode 4

7 - 4: Sangre Por Sangre

Members of El Puno, a Puerto Rican gang, are found murdered only days after the release of its founder, Luther Devarro (Edward James Olmos), whom Mac arrested for murder several years earlier. Believing a rival gang is responsible, Mac asks Devarro for help in solving the murders, concerned that the NYPD may have a gang war on their hands. Later, El Puno's headquarters is destroyed in an explosion. Over the course of the investigation, Mac learns it was Devarro who killed his own gang members. In the final showdown, Devarro admits that when his brother took charge, he grew disgusted over the fact that his gang turned more violent and ruthless. Devarro kills his brother, and Mac, believing Devarro shot at him and missed, fatally shoots him.