Laurence Fishburne by Jordan Strauss/ Laurence Fishburne by Jordan Strauss/

Film vet Laurence Fishburne is close to signing a deal to join CBS' CSI, sources tell Fishburne would fill the considerable void being left when series front man William Petersen steps down after this season's 10th episode.

Fishburne will play a doctor/scientist who comes into the CSI as an outsider, and not as the team's new boss, CBS Entertainment president Nina Tassler revealed at the TCA press tour. As a DNA expert, this new character has identified a common profile among serial killers - and it's even in his own genes.

Petersen - who will continue on as an executive producer as well as put in the occasional "special" appearance - is the third original cast member to leave the show, following Jorja Fox and Gary Dourdan (each of whom will briefly resurface this season). - Matt Mitovich, with reporting by Craig Tomashoff and Mickey O'Connor

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