'Criminal Minds' season 12 spoilers: Mr. Scratch, Spencer's mother to return

Mr. Scratch (Bodhi Elfman) is nowhere near done with his reign of terror. In fact, he will be back in "Criminal Minds" season 12 for what is looking to be the lengthiest arc of the season.

Executive producer Erica Messer spoke to TV Guide with regard to, among others, the infamous criminal's return during the back nine of the season.

"I think it's going to be surprising for everybody and incredibly rewarding for everybody who's watched for as long as they have," she said of the "Criminal Minds" season 12 arc on Mr. Scratch.

"To have a more serialized arc for our heroes to deal with is definitely going to be different for us and challenging and for viewers, you might not believe where we're going," Messer went on to say.

The last time he struck, Mr. Scratch, whose real name is Peter Lewis, messed with Tara (Aisha Tyler) early in "Criminal Minds" season 12, by kidnapping her brother, Gabriel (Terrence Terrell), employing another man to pretend as him and then booby-trapping the warehouse where he put the real Gabriel so Tara could not save him.

What Mr. Scratch will do next when he returns in "Criminal Minds" season 12 remains to be seen, but it looks like he is cooking up his biggest scheme yet.

Apart from Mr. Scratch, another familiar face will return in "Criminal Minds" season 12 and that is Jane Lynch as Spencer's (Matthew Gray Gubler) mother.

Lynch will appear in three episodes of "Criminal Minds" season 12 beginning with the upcoming episode set to air Feb. 1, "Surface Tension."

As revealed before, there will be a Spencer-centric episode to be written by cast member Kirsten Vangsness. This one will likely be the third episode Lynch will appear in.

After expressing her excitement to finally see Lynch reprise her role, Messer teased that her return will be the center of an "amazing story."