It was revealed earlier this week that actor William Petersen would end his run on the hit CBS procedural “CSI” after eight years of portraying insightful investigator Gil Grissom and the network promises a captivating new character in exchange.

CBS Entertainment President Nina Tassler told members of the Television Critics Association on Friday that William Petersen’s exit from “CSI: Crime Scene Investigation” was not a sudden one but rather a move the network had been preparing for, reports the New York Daily News.

Tassler said CBS had been discussing the issue “strategically” for a while and that while Petersen can’t be replaced, “you look at adding elements to the show that are really going to invigorate and contribute to the alchemy of where it is today.”

The invigorating solution the show’s producers have found is to introduce a character that will keep viewers wondering on his true nature and frame of mind.

Tassler revealed the new character would be a scientist whose genetic makeup could possibly predispose him to be a serial killer. The character’s story line will center heavily on this enigmatic situation.

An actor has not been cast yet for the part. Tassler did confirm though that “The L Word's” Laura Lee Smith was joining the cast for the show’s ninth season, which premieres Oct. 9 at 9 p.m.

William Petersen remains executive producer of “CSI” and will also return for future guest star appearances. He will star as a full-time series regular for the last time on the upcoming season’s 10th episode, after which he will pursue other creative interests.

He is scheduled to appear in the play “Dublin Carol” in Chicago later this year.

Petersen told Entertainment Weekly last week that he feels he is “in a great place in terms of knowing that I’ll be more free to make choices.” The actor added that he is “responsible enough to not do it in a way that would hurt [the show].”

“I want it to work for the writers, I want it to work for the cast, and, most importantly, I want it to work for the audience. I don't want them to abandon the show,” Petersen said. The actor previously took a break from the show during the 2006-07 season to perform in a play. During that period, Liev Schreiber joined the cast as a visiting investigator.