
Sarah Michelle Gellar has joined the cast of Dexter: Original Sin in a special guest-starring role.
Gellar is set to play Tanya Martin, the CSI Chief at the Miami Metro Police Department aka Dexter's new Boss. The prequel series stars Patrick Gibson as a young Dexter Morgan, with Christian Slater set to play his adoptive father Harry and Molly Brown (Senior Year) set to play a young Debra Morgan. Patrick Dempsey and Christina Milian have also joined the cast (H/T Deadline).