‘Criminal Minds’ Spoilers: An Old Serial Killer Is Coming Back For Season 12B? CBS Series To Become Serialized

When “Criminal Minds” returns to CBS on Thursday, it will be a slightly different show. For starters, the back half of Season 12 be serialized.

“It feels like we’ve earned the right to tell some serialized stories,” the series’ executive producer Erica Messer told TVLine, “so we’re running with that, telling a really big arc that will last all of the back 9 [episodes] of Season 12.”

Of course, as previously reported, Dr. Spencer Reid (Matthew Gray Gubler) will play a significant role in this new serialized arc. The triple Ph.D. holder will take his Alzheimer-afflicted mother Diana (Jane Lynch) home. Messer said that the Reid-centric storyline launches an intense journey not only for the genius but also for the team.

The producer also revealed that in the second half of “Criminal Minds” Season 12, a familiar serial killer from the BAU’s (Behavioral Analysis Unit) past will be back. Messer said that this old serial killer will be similar to Mr. Scratch and Tommy Yates. Who could it be?

Messer said, “Oh my gosh — if I said who [is returning], I would possibly give more away than I want to give away. But we’re really acknowledging the history of the series and being able to bring back people who have made an impact, good or bad, on our characters. And we’re having a really good time doing that.”

Reid’s mother is set to make an appearance in episodes 11, 13 and 20. While episode 11 will see Reid take his mother out of the clinical study, episode 13, titled “Spencer,” will see him trapped in a jail in Mexico. It is also a crossover episode with “Criminal Minds: Beyond Borders” since two actors from the spin-off will be seen.

“Criminal Minds” fans are wondering which serial killer could be back, particularly one that has personally affected Reid since both Mr. Scratch and Yates struck a vein with BAU members Hotch (Thomas Gibson) and Rossi (Joe Mantegna) respectively.

Could Cat Adams (Aubrey Plaza) or Amanda/Adam Jackson (Jackson Rathbone and Milissa Skoro) be back? After all, both murderers were somehow close to Reid.

“Criminal Minds” Season 12 returns Wednesday, Feb. 1 at 9 p.m. EST on CBS.