Patrick Dempsey has joined the cast of the upcoming prequel series 'Dexter: Original Sin,' set in 1991 Miami and focusing on a young Dexter Morgan transitioning into a vigilante serial killer guided by his father's Code. Dempsey will play Aaron Spencer, the Captain of Miami Metro Homicide with ties to Dexter's father, Christian Slater's Harry Morgan. The show, produced by Showtime Studios and Counterpart Studios, features a star-studded cast including Patrick Gibson, Molly Brown, James Martinez, Christina Milian, Alex Shimizu, and Reno Wilson. Clyde Phillips, the original showrunner, returns as the showrunner and executive producer. The prequel series marks the third installment in the Dexter franchise, following the original series that aired from 2006 to 2013.