CSI: Crime Scene Investigation physical evidence to solve murders. The team is originally led by Gil Grissom (Petersen), a socially awkward forensic entomologist and career criminalist who is promoted to CSI supervisor following the death of a trainee investigator. Grissom's second-in-command, Catherine Willows (Marg Helgenberger), is a single mother with a cop's instinct. Born and raised in Las Vegas, Catherine was a stripper before being recruited into law enforcement and training as a blood-spatter specialist. Following Grissom's departure during the ninth season of the series, Catherine is promoted to supervisor. After overseeing the training of new investigator Raymond Langston (Fishburne), Willows is replaced by
CSI: Crime Scene Investigation Hall, and California State University, Los Angeles. While shooting took place primarily at Universal Studios in Universal City, California, Santa Clarita's surroundings had proven so versatile, "CSI" still shot some outdoor scenes there. "CSI"'s theme song was, since the last episode of season one, "Who Are You", written by Pete Townshend with vocals by lead singer Roger Daltrey of The Who. Daltrey made a special appearance in the episode "Living Legend", which also contained many musical references such as the words "Who's next" on a dry-erase board in the episode's opening sequence. In certain countries, to avoid music licensing fees,