Turns out that contract William Peterson inked last March wasn’t a long-term one. Michael Ausiello of Entertainment Weekly is reporting that the actor will be gone by midseason. His 10th episode will be his last as a full-time regular.
“Billy is leaving,” confirms the show’s executive producer, Carol Mendelsohn. “But he will remain throughout the run of the series an executive producer. And he will, whenever CBS asks, come back. I don’t think you’ve seen the last of Gil Grissom.”
Source: Entertainment Weekly