Gilbert Arthur Grissom (born August 17, 1956), Ph.D. is a fictional character portrayed by William Petersen on the CBS crime drama CSI: Crime Scene Investigation and its sequel, CSI: Vegas. Grissom is a forensic entomologist and, for the series' first nine seasons, a CSI Level III Supervisor employed by the Las Vegas Police Department. He appeared in 198 episodes , and was succeeded by Raymond Langston (Laurence Fishburne) and , later , D.B. Russell (Ted Danson).  Appearances Series regular Petersen appeared in every episode of the  series' first eight seasons, with the exceptions of:
Gilbert Arthur Grissom (born August 17, 1956), Ph.D. is a fictional character portrayed by William Petersen on the CBS crime drama CSI: Crime Scene Investigation and its sequel, CSI: Vegas. Grissom is a forensic entomologist and, for the series' first nine seasons, a CSI Level III Supervisor employed by the Las Vegas Police Department. He appeared in 198 episodes of the original series, where he was succeeded by Raymond Langston (Laurence Fishburne) and later D.B. Russell (Ted Danson). Grissom will return in the CSI: Vegas sequel in 2021. Appearances Series regular Petersen appeared in every episode of the original series' first eight seasons, with the exceptions of:
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Grissom will return in the CSI: Vegas sequel in 2021.
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