Nick Stokes, a CSI level III (regular: seasons 1–15)Stokes graduated from Texas A&M and joined the Dallas Police prior to moving to Las Vegas. He was promoted to CSI level III in the pilot episode of the series and later became assistant night supervisor under Catherine Willows. Stokes was later demoted, and after remaining in Las Vegas a CSI III, he transfers to San Diego when he is granted the directorship of the SDPD Crime Lab. Jorja Fox as Sara Sidle, a CSI level III (regular: seasons 1 (from episode 2 "Cool Change")–8 (until episode 7, "Goodbye & Good Luck"), 11–15, "Immortality"; recurring: seasons 9 (occasionally), 10 (regularly as Special Guest Star)) Sara is a materials and element analyst who majored in physics at Harvard University. Sara transferred from San Francisco at the behest of Grissom, whom she later marries. After a turbulent relationship and a divorce, Sara is promoted to director of the Las Vegas Crime Lab, though she relinquishes this position to reunite with her ex-husband, Grissom. Catherine then succeeds her as lab director. Eric Szmanda as Greg Sanders, a CSI level III (regular: seasons 3–15, "Immortality"; recurring: seasons 1–2) Greg is a DNA specialist who was educated in a private school for gifted students. Graduating Phi Beta Kappa from Stanford, Sanders joined the LVPD after a short stint with the SFPD. He later wrote a book about the history of Las Vegas. Greg believes in psychic powers, and is willing to sacrifice himself for what is right. Over the course of the series, Greg has several love interests. He expressed a romantic interest in fellow CSI Morgan Brody after meeting her in season 12. Robert David Hall as Dr. Albert "Al" Robbins, the chief medical examiner (regular: seasons 3–15, "Immortality"; recurring: seasons 1–2) Robbins is the head county coroner of the LVPD. He is married with three children and has prosthetic legs, having lost his own legs after being hit by a drunk driver as a teenager. Al rarely leaves the crime lab, instead performing autopsies and referring specimens for forensic analysis. He forms strong bonds with both Gil Grissom and Raymond Langston. Paul Guilfoyle as LVPD Captain Jim Brass, homicide detective captain (regular: seasons 1–14, "Immortality")Brass was initially the CSI team's supervisor until losing the position after Holly Gribbs, a rookie CSI under his command, is murdered on her first day on the job. He is