The police procedural CSI: Crime Scene Investigation aired on CBS for 15 seasons, from 2000 to 2015, and spawned three spinoff shows: CSI: Miami, CSI: NY and CSI: Cyber. CSI not only boasted a large number of episodes and successes, it also had quite a substantial cast, meaning many of the actors rotated out of the series throughout its run. One such actor was William Peterson, who played Gil Grissom. After starring in nine seasons, the actor known for such films as To Live and Die in L.A. and Manhunter decided to call it quits due to a realization he had about his career.
Who Was CSI's Gil Grissom?
CSI followed a team of crime scene investigators for the Las Vegas Police Department, led by Gil Grissom. He was a forensic entomologist and career criminalist whose intellect and reserved demeanor were perfect for the role. However, Gil's social awkwardness and tendency to be unemotional caused him to have difficulty relating to others.
Throughout CSI, Gil got close and personal with some of the crimes. In Season 1, he came face-to-face with the serial killer he was trying to capture and was almost killed by him before Catherine Willows saved the day.
A major arc for Gil was his hearing loss. CSI spent time in Seasons 2, 3 and 4 fleshing out this storyline. Apparently, Gil had Otosclerosis, a degenerative disease he inherited from his mother. In Season 3, he underwent surgery for his hearing loss, and Season 4 revealed the operation was successful. Gil continued his work as before.
By the time Season 7 rolled around, Gil was showing signs of burnout, and left on sabbatical to teach at Williams College in Massachusetts. He did return, however, and continued as part of the team. But in Season 9, Episode 10, "One to Go," Gil announced his retirement to the team. Thus, his actor, William Petersen, left CSI as a regular member of the cast but remained as an executive producer. He returned as a guest star in the Season 11 episode "The Two Mrs. Grissoms" before making his final appearance, in the 2015 series finale/TV movie, "Immortality."
Why William Petersen Left CSI
In short, Petersen left CSI because he believed he was becoming "too comfortable" in the role, and wanted to pursue other opportunities. Because his role was so solidified in the long-running series, the job became monotonous, and he felt as though he wasn't growing as an actor. "It's CSI — they pay me a lot of money, and I don't have to work very hard anymore. I've got it all figured out," Petersen told said in a 2009 interview. "And I just realized, God, as an artist, I'm going to atrophy. You do anything for nine years, it becomes somewhat rote."
Petersen decided the best way to expand his craft was to pursue theater. And he did just that. He had starred in a multitude of stage productions prior to CSI, and after his departure from the show, he added to his resume. He starred in productions such as Endgame, Slowgirl and The Minutes. He even won a Jeff Award for his performance in Blackbird.
William Petersen's Return as Grissom on CSI: Vegas
The end of CSI wasn't the end of Grissom, however. Six years after the 2015 series finale, Petersen will return to the role in CSI: Vegas. The direct sequel to CSI will reunite Petersen with former co-star Jorja Fox, who reprises her role as Sara Sidle. Wallace Langham also returns as lab technician David Hodges, while fellow CSI veteran Paul Guilfoyle will guest-star in a pair of episodes as Jim Brass.
Originally intended to premiere in October 2020, to commemorate the 20th anniversary of CSI: Crime Scene Investigation, CSI: Vegas was delayed due to a COVID-19 production shutdown. The series will now debut Wednesday, Oct. 6, 2021, on CBS.