'Criminal Minds' season 12 episode 11 spoilers: BAU investigates strange hieroglyph; showrunner teases Jane Lynch's multiple-episode arc

The BAU investigates a bizarre hieroglyph on the upcoming episode of "Criminal Minds" season 12.

Titled "Surface Tension," the show's next episode features the return of a familiar face. According to the official synopsis, a strange hieroglyph is found under a deceased homeless man's armpit. While the team looks for pieces of evidence, they discover that the symbol is the same from previous casualties years ago.

Meanwhile, Reid (Matthew Gray Gubler) decides that his mother no longer needs to be a part of a clinical study, so he takes her home to live with him. Veteran actress Jane Lynch returns to guest star as Diana Reid, Dr. Reid's troubled mother.

Lynch, who is known for her roles in "Glee" and "The Fugitive," first appeared on the hit CBS procedural in 2006. This season, Lynch makes her "Criminal Minds" comeback for a multi-episode arc. Showrunner Erica Messer recently caught up with TV Line, and she revealed that the first of Lynch's multiple appearances somehow "resets for us where Reid is with is with his mom and her struggle."

Diana was previously admitted to a groundbreaking Alzheimer's treatment study. However, she was recently found wandering in Vegas after being dropped from the program because of budget cuts. Messer co-wrote one of the upcoming Reid-centric episodes with cast member Kirsten Vangsness, and she hinted that it will see a major turning point for Reid.

"It turns out [Kirsten] and I go big. It is absolutely a change of course [for Reid] — a journey, for him and for the team, that I would argue we never even imagined would happen," the showrunner said, adding, "And yet it happens, and we're along for this ride. And it's an intense one."

The 12th season of "Criminal Minds" airs every Wednesday night at 9 p.m. ET on CBS.