EXCLUSIVE: Rachel Nichols is in negotiations to join the cast of CBS’ Criminal Minds as a series regular, the show’s first new regular addition since Joe Mantegna took over for Mandy Patinkin in 2007. Nicholson was originally tapped for a 3-episode arc, which will begin airing next week. CBS had said it would add a new female regular cast member this season following the departure of original co-star A.J. Cook. The character Alias alumna Nichols will play, FBI cadet Ashley Seaver, had been originally listed as a new regular but was eventually scaled back to 3 episodes. Seaver will first join the Behavior Analysis Unit when she is invited by Agent Hotch (Thomas Gibson)  to consult on a case after learning her family history will bring a unique insight into the mind of a serial killer.

Meanwhile, I hear Paget Brewster has been asked to return to a status of a full-fledged regular on the show but will weigh pilot offers. Following the cast upheaval on the veteran CBS crime drama over the summer, Brewster was offered to return to the show this season as a regular but in reduced capacity, appearing in about 17 of the series’ 22 episodes. As part of the new deal she signed, Brewster was given a “pilot out,” meaning she could do a pilot for a new series while on Minds this season. Brewster has appeared in all 9 episodes of the CBS drama that have aired so far, and the network recently proposed a return to the original agreement. Brewster opted to adhere to her amended contract and take advantage of the option that allows her to do a pilot.