'The Mentalist' Season 6 Spoilers: Rockmond Dunbar to Join Cast

Former "Prison Break" inmate Rockmond Dunbar has joined the CBS hit show "The Mentalist." Dunbar is joining the show to assume a role that could potentially be a series regular spot. 

TVLine reports thats Dunbar has been cast as Dennis Abbot, a hardline FBI Supervisory Agent who is not impressed by Patrick Jane's (Simon Baker) detective skills or disarming charisma. Dunbar has also appeared on "Sons of Anarchy," "The Game" and the canceled show "Terriers." 

Abbott is one of two characters who are being added to the show for the sixth season in preparation for the midseason exits of Amanda Righetti, who plays Grace Van Pelt, and Owain Yeoman, who plays Wayne Rigsby. The characters are on-again, off-again lovers who will exit due to something in connection with the unmasking of the elusive Red John. The solving of the six-year-old mystery will set the show in a new direction. 

The other character who is replacing the popular pair is FBI agent Kim Fischer, a tough ex-homicide detective in her mid-thirties who hails from Dallas. The part of Kim Fischer has not yet been cast. 

One of the new characters introduced will have a negative impact on what fans lovingly call "Jisbon": the relationship between Patrick Jane and Teresa Lisbon (Robin Tunney). 

It was hinted that the arrival of a new, major female character in 2014 will complicate Jane's relationship with Lisbon. The conclusion of the Red John mystery will also affect their relationship. 

Series creator Bruno Heller said, "Up until now, they've been tied by this professional dynamic and this mission they're on. And that held their personal relationship in suspense. Once the Red John saga is done, how do they find a new way to relate to each other? The chemistry has always been there bubbling up. But he now has other priorities and other agendas and other pressures."

Jane considers leaving the whole profession after the reveal, but the new character may convince him to stay. 

"The Mentalist" debuts its sixth season on Sunday, Sept. 29 on CBS.