In an interview with CNN in 2009, Petersen revealed that he’d become comfortable in the role, perhaps a bit too comfortable: “I didn’t want to be on the show because it saved me from having to go look for other jobs. Just didn’t want it. It was too safe for me at this point. So I needed to try and break that, and the way to do that, for me, is the theater.” Petersen would return to the theater to trod the stage in a number of productions in Chicago, where he continues to perform to this day.
Petersen also left “CSI” because he also felt the character of Grissom had reached a natural ending point: “It was a complete life for me that’s reached its end, and it’s reached it in the right way, I think. So I won’t miss Grissom. And I hope that the audience won’t miss him either.”
It’s understandable that Petersen would choose to leave “CSI” on his own terms and for his own creative fulfillment. Sometimes it really is best to go out while you’re on top.