'Criminal Minds' season 12 news: Paget Brewster returns; Thomas Gibson appears one last time

Emily Prentiss is back at the Behavioral Analysis Unit (BAUU).

In the third episode of "Criminal Minds" season 12, Prentiss (Paget Brewster), now an Interpol unit chief, arrived to help the FBI's BAU hunt down an escaped serial killer.

Brewster, who was a "Criminal Minds" series regular between seasons 2 and 6, and later appeared as a special guest star in seasons 9 and 11, was only supposed to have a recurring arc spanning six episodes in the current season of the police procedural drama.

However, after original cast member Thomas Gibson's firing in August, Brewster was promoted to a main cast member. The actress made her grand "Criminal Minds" homecoming in Wednesday's episode, titled "Taboo."

In the episode, BAU Chief Aaron Hotchner (Gibson) was temporarily sent away on a special assignment. In his absence, Prentiss was called in to aid the BAU team members with a new case, one that was added to their normal workload.

According to TV Line, before "Criminal Minds" decided to fire Gibson, Hotchner was supposed to be on his special mission for only an episode or two. This was set up to accommodate the period in which Gibson was suspended after an on-set altercation with a "Criminal Minds" producer. But because he was eventually fired, Brewster's originally short-term guest role became a permanent gig.

In an interview with CBS, "Criminal Minds" executive producer Erica Messer said Brewster was promoted because Prentiss is a fan-favorite character.

"She's been running Interpol for four years, and now it's just really nice to be back on the team full-time," Brewster said about her character's return. "So far, they've made [Prentiss] powerful and good at the job and invested."

In addition to Brewster's return, "Criminal Minds" also created a new character, a seasoned criminal profiler named Stephen Walker, who will be played by "Bates Motel" actor Damon Gupton.

According to "Criminal Minds" cast member A.J. Cook (Jennifer "JJ" Jareau), the crime drama is able to continue on year after year because it's "finding new personalities that fit into this machine that works really well and we've been lucky enough to find those pieces."

Meanwhile, Gibson recently explained the on-set incident that led to his firing, telling People that he and the "Criminal Minds" producer "had some choice words, for which I apologized the next day, and that was it."

"We shot the scene, I went home — and I never got to go back," he said.

"Criminal Minds" season 12 airs Wednesdays at 9 p.m. EDT on CBS.