CSI: Crime Scene Investigation is an American crime drama television series. CSI premiered on CBS on October 6, 2000. The ninth season began airing on October 9, 2008 and currently airs in the United States on Thursdays at 9:00 p.m. The show was created by Anthony E. Zuiker and produced by Jerry Bruckheimer. It is filmed primarily at Universal Studios in Universal City, California.
CSI trails the investigations of a team of Las Vegas forensic scientists as they unveil the circumstances behind mysterious and unusual deaths and other crimes. For the first eight and a half seasons, the show starred William Petersen as Dr. Gil Grissom, the night shift supervisor who excels in crime scene investigation. In the middle of the ninth season, Petersen left and was replaced by Laurence Fishburne as Dr. Raymond Langston, a former medical doctor who turns criminalist in an attempt to rid himself of past demons.

The show follows the cases of the Crime Scene Investigation division of the Las Vegas Police Department, usually referred to by officers as the "Las Vegas Crime Lab." Anthony E. Zuiker chose to set the series in Las Vegas because—as mentioned in the pilot—that city's crime lab is the second most active in the United States, after the Federal Bureau of Investigation lab in Quantico, Virginia.The division solves crimes almost entirely through forensics evidence, which may or may not come to conclusion of a murder or accidental death. The bizarre conclusions of these cases often force one to question morals, beliefs and human nature in general.