Paul Thomasch

LOS ANGELES (Reuters) - Actor William Petersen's exit from the CBS hit "CSI: Crime Scene Investigation" opens the door for a new character to join the show's crime-busting team -- only this one just could be a crazed killer.

CBS's programming chief, Nina Tassler, on Friday confirmed Petersen's plans to leave the show at the mid-point of the upcoming TV season, after the first 10 episodes.

Unlike Petersen's character, Gil Grissom, a brainy investigator who heads a Las Vegas crime unit, the show's new addition will be a scientist with a dark secret -- his genetic makeup is similar to that of known killers.

"He comes in not immediately as the boss, but he has an interesting genetic profile that in certain sort of medical contexts, they've noticed that many times serial killers have that same genetic profile," Tassler told a gathering of TV critics in Beverly Hills.

"This gentleman knows this about himself and is sort of in this journey and -- and to discover who his true character will ultimately become," she said.

The role has yet to be cast.

Petersen, who also is an executive producer of the show, will return for future guest star appearances but is interested in other creative pursuits, Tassler said. Petersen is due to appear in the play "Dublin Carol" in Chicago later this year.

"CSI," the top-rated CBS series last season, premiered in 2000 and spawned popular spin-offs "CSI: Miami" and "CSI: NY."