Deadline reports the Emmy-winning actor will play police chief Sam Chapel who oversees the San Francisco Police Department's Gang Task Force. O'Quinn replaces Tom Berenger ("Hatfields & McCoys") in the role after the actor exited the project following the first cast table read.
Ramon Rodriguez also stars in the pilot written by Chris Morgan, directed by Allen Hughes and executive produced by Brian Grazer.
O'Quinn has been a steady presence on TV since his "Lost" role as John Locke made him a star. He headlined ABC's doomed "666 Park Avenue" this season and also had recurring roles on CBS' "Hawaii Five-0" and TNT's "Falling Skies." His past TV credits include "The West Wing," "Alias," "Jag" and "Millennium."