'Criminal Minds' season 12 spoilers, cast updates: Paget Brewster returns as series regular; Emily Prentiss to be next BAU chief?

After a major behind-the-scenes shakeup involving the exit of Thomas Gibson, "Criminal Minds" season 12 is all-set to return with Paget Brewster reprising his role as a series regular again.

Brewster, who was previously announced to rejoin the series as a guest star for a multi-episode arc, has been recently upped to series regular. She will be back as Supervisory Special Agent Emily Prentiss, who teams up with the BAU right when they need her the most after 13 serial killers have escaped. Her first appearance for season 12 is tentatively scheduled to air on Wednesday, Oct. 2.

"We're all so excited to have Paget with us full time," executive producer/showrunner Erica Messer told Deadline. "The BAU family has definitely missed her, on screen and off. Having her back on set has been great, it's like she never left."

There are speculations that Brewster's character will fill the void left by actor Thomas Gibson and become the BAU's next team leader. Gibson, who portrays the role of Aaron "Hotch" Hotchner, was recently dismissed after an on-set altercation with producer/writer Virgil Williams.

Since Gibson's departure was unexpected, viewers are now wondering how his dismissal will be addressed in the story. Although execs have previously confirmed that the plot will explain why Hotch will no longer return, rumor has it that he will either be killed off or just mysteriously disappear. If one thing is for certain, the veteran actor's exit will have an effect on the story and draw different reactions from the audience once the program airs.

Also joining next season as a series regular is Aisha Tyler, who plays the role of Dr. Tara Lewis. Newcomer Adam Rodriguez is the show's latest addition and he will play FBI Agent Luke Alvez.

Catch all-new episodes of "Criminal Minds" season1 2 which premieres on Wednesday, Sept. 28 at 9 p.m. EST on CBS.