The Grey's Anatomy star is set to play Aaron Spencer, the Captain of the Miami Metro Homicide department who has a decades-long relationship with Dexter's adoptive dad, Harry Morgan, portrayed by Christian Slater (via Deadline ).

Patrick Dempsy, popularly known for playing the character of Derek Shepard in the medical drama Grey’s Anatomy, is set to join the cast of Original Sin, the prequel to the Paramount series Original Sin.

Patrick Gibson from Shadow and Bone will play Dexter in the new series, while Molly Brown has been cast as Debra Morgan, James Martinez as Angel Batista, Christina Milian as Maria LaGuerta, Alex Shimizu as Vince Masuka and Reno Wilson as Bobby Watt. Dexter showrunner Clyde Phillips is returning for the prequel series.

Patrick Dempsey ( Grey’s Anatomy , Enchanted , Ferrari ) has joined the cast of the Paramount+ with Showtimes series Dexter: Original Sin in a series regular role. In the Dexter prequel series, Dempsey will play Aaron Spencer,

The Dexter prequel series, Dexter: Original Sin, already has a number of cameos from characters of the existing show, and it’s adding a new, but familiar star, Patrick Dempsey, most known for playing Derek Shepherd in Grey’s Anatomy, as Aaron Spencer, Captain of the Miami Metro Homicide Department.

Yes, according to a new report from Variety, Patrick Dempsey has joined the cast of Dexter: Original Sin. The prequel series, which focuses on the titular antihero's origin story, began production in Miami earlier this month. Dempsey will play Aaron Spencer, a captain for the Miami Metro Homicide division.

Patrick Dempsey (Grey's Anatomy) has joined the cast of Paramount+ with Showtimes’ Dexter: Original Sin in a series regular role. In the Dexter prequel series, Dempsey will play Aaron Spencer, the Captain of the Miami Metro Homicide department who has a decades-long relationship with Harry Morgan (Christian Slater).

Patrick Dempsey is fleshing out the cast of the upcoming serial killer series Dexter: Original Sin. The 58-year-old Grey's Anatomy star is joining the prequel series as a main cast member, according to Variety.