The Dexter Season 5 production machine must be working overtime - building one of the strongest supporting casts in the show's history.

Today, we're getting word that British actor Chris Vance, best known for his role as James Whistler in Prison Break, will be joining Dexter for at least three episodes.

According to The Ausiello Files, Vance will play a character named Cole: "a meticulous, physically fit, well-spoken personal aide to a famous businessman."

Besides his notable performance as SONA inmate James Whistler, Vance has also starred as Mason Gilroy in a five episode Burn Notice arc. International audiences might recognize Vance as Jack Gallagher, the starring role in Fox Telecolombia's Mental, which aired in several international markets including Asia, Europe, and Latin America in 2009.

Vance is a great addition to a cast which already includes guest appearances by Julia Stiles (The Bourne Ultimatum), Peter Weller (RoboCop), Jonny Lee Miller (Eli Stone), Shawn Hatosy (Southland), and Maria Doyle Kennedy (The Tudors).

Dexter Trinity Killer John Lithgow

Considering the response to John Lithgow's Season 4 performance as the unforgettable Trinity Killer, it's no surprise that the Dexter show-runners are looking to capitalize on a-list TV talent to maintain the show's momentum. The Dexter producers have repeatedly mentioned that Season 5 will not feature a "big bad" (read: major serial killer - i.e. Ice Truck or Trinity Killer) - so the supporting ensemble will be more important than ever.

Official details have been slim and most everything we know has been drawn from the Comic-Con teaser trailer but, considering the strong supporting cast, it'll be interesting to see how the new characters play into the upcoming story.

Dexter Season 5

Needless to say, season 4 Dexter spoilers ahead:

In addition to the usual adventures of Dexter's Dark passenger, Season 5 is expected to revolve around Dexter's Kyle Butler alias, the disappearance of Arthur Mitchell aka the Trinity Killer, as well as the circumstances surrounding Rita's death - with Dexter emerging as a potential suspect.

Dexter Season 5 will debut on September 26, 2010 exclusively on Showtime.

In the mean time, see how Dexter stacks up against the world's less-likable serial killers.

Source: The Ausiello Files