Former Third Watch star Bobby Cannavale has been added to the cast of CBS' new cop drama Blue Bloods, TVGuide.com has learned exclusively.

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Cannavale will play Charles Rosselini, the boss of Bridget Moynahan's Assistant District Attorney Erin Reagan. Rosselini is the talented and popular Manhattan DA. He has political ambitions, but as an ex-cop who served nearly 10 on the force before finishing law school, he remains a bit rough around the edges.

Blue Bloods, a procedural about a multigenerational clan of New York cops, stars Tom Selleck as the patriarch and chief of police, a title his father (Len Cariou) previously held. His two sons (Donnie Wahlberg and Will Estes) are also in the NYPD, while his daughter, Erin, is a single mother working in the DA's office.

Cannavale is best known for his work on Third Watch and his Emmy-winning recurring role as Will's boyfriend on Will & Grace. More recently, he guest-starred on Cold Case and headlined ABC's short-lived 2009 revival of Cupid. The 39-year-old actor, whose film credits include The Station Agent and Snakes on a Plane, currently can be seen on the big screen in The Other Guys.

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Cannavale's character will first appear in the freshman drama's Oct. 15 episode. Blue Bloods premieres Friday, Sept. 24 at 10/9c on CBS.