of Las Vegas; after episode 11, filming shifted to the nearby Santa Clarita Studios. Occasionally, the cast still shot on location in Las Vegas (the season-four DVD set revealed that the episode "Suckers" was mostly shot during December 2003 in Las Vegas, where they filmed a Gothic club scene on location for rent, and in January 2004, some scenes were filmed at Caesars Palace), although Las Vegas was primarily used for second unit photography such as exterior shots of streets. Other California locations include Verdugo Hills High School, UCLA's Royce Hall, Pasadena City Hall, and California State University, Los Angeles. After season five, CSI episodes were primarily filmed at Universal Studios Hollywood in Universal City, California, but since Santa Clarita's surroundings had proven so versatile, CSI continued to shoot some outdoor scenes there. Music CSI's theme song was "Who Are You", written by Pete Townshend with vocals by lead singer Roger Daltrey of The Who. Daltrey made a special appearance in the season-seven 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, a unique theme was used, instead. Throughout the series, music played an important role; artists such as Ozzy Osbourne, The Wallflowers, John Mayer, and Akon (with Obie Trice) performed onscreen in the episodes "Skin in the Game", "The Accused Is Entitled", "Built to Kill, Part 1", and "Poppin' Tags", respectively. Mogwai was often heard during scenes showing forensic tests in progress, as were Radiohead and Cocteau Twins, but several other artists lent their music to CSI, including Rammstein and Linkin Park—used heavily in Lady Heather's story arc. Sigur Rós can be heard playing in the background in the episode "Slaves of Las Vegas", The Turtles in "Grave Danger", and Marilyn Manson in "Suckers". A cover of the Tears for Fears song "Mad World", arranged by Michael Andrews and featuring vocals by Gary Jules, was used in the pilot episode and during three episodes of season six ("Room Service", "Killer", and "Way to Go"). Industrial rock band Nine Inch Nails was also featured multiple times throughout the three series. One episode started with The Velvet Underground's excited rendition of "Sweet Jane" and ended with the downbeat version of Cowboy Junkies' revision of the song. Character David Hodges' good luck has, on occasion, been accompanied by Electric