Mario Orozco

Brenda follows the trail of a suspected sniper who is assassinating members of the East Side Catorces, one of the city's most notorious gangs. When a retired U.S. Marine Corps colonel comes forward at the first crime scene and offers detailed information about the murders, Brenda agrees to work with him secretly to avoid scaring off the suspect. But as the case unravels, she begins to think there is more to the colonel's story than he has revealed. After more killings happen, Brenda asks Fritz to help her catch the sniper.

The CSI team races to track down a medevac helicopter that was hijacked -- with Morgan Brody on board.

Residency Director Dr. Leanne Rorish (Marcia Gay Harden) puts her four new first year residents to work immediately on their first day at Angels Memorial Hospital, in the busiest, most notorious hospital ER in the nation.