It's official: CSI has landed in the water after jumping the shark: Apparently it's all gotten to be too much for Crime Scene Investigator Gil Grissom. Or, it will. Calling it an actual signoff rather than yet another sabbatical, EW.com reports that William Petersen will be leaving CSI sometime midseason . "Billy is leaving," series executive producer Carol Mendelsohn said. "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." Right... Gil, whoops, Will, will join fellow co-stars Jorja "fights for circus animal rights" Fox and Gary "not going to rehab" Dourdan in the "Why did we leave the most high-profile roles we ever landed" wilderness. From EW.com His sorta swan song, coupled with Jorja Fox and Gary Dourdan's exits last season, brings to three the number of original cast members CSI will have lost in a year's time. "This will be a year of transition for the show," concedes Mendehlson. "We always knew it was coming, and I'm glad it didn't come until now." At this point, she's confident that, like Law & Order and ER, CSI is a franchise that can weather such cast shifts. Now if only David "wait, I'm popular, I even have a stalker" Caruso would develop creative differences with CSI Miami... Photo: Handout/CBS ...