Laurence Fishburne by Jemal Countess/ Laurence Fishburne by Jemal Countess/

The deal is done for Laurence Fishburne to join CBS' CSI, filling the void that will be left by William Petersen's exit.

Fishburne will debut in this season's ninth episode - very tentatively slated to air Dec. 11, around the same time that Gil will go bye-bye - playing a former pathologist who is now teaching a college course in criminalistics. In the midst of a murder investigation, his character crosses paths with Grissom's team and ultimately joins the Las Vegas crime lab as a Level-1 CSI.

"Gil will definitely have an opinion on who this guy is," exec producer Naren Shankar previews for "The idea is, in Episodes 9 and 10, to see a lot of Billy and Laurence together."

As previously teased, Fishburne's alter ego (who is currently nameless and referred to simply as "the Professor" in the CSI writers room) is an expert at understanding how and why people commit acts of violence tendencies he sees within himself. That said, previous reports that this newcomer shares a DNA trait with serial killers are not accurate. "In reality there is no such thing," says Shankar. "He is a character who has been able to examine his own genetic profile [and] find certain clusters of biological facts that... are associated with aggressiveness or criminal behavior. That's all it is."

Shankar and fellow CSI executive producer Carol Mendelsohn say that Fishburne topped their wish list for the role, calling him "a powerful and intense actor with an incredible range."

"If you distill CSI down to its essence, it's a collaboration," a statement from the two says, "and we are so looking forward to collaborating with Mr. Fishburne. For all of us at CSI, this is truly a dream." - Matt Mitovich