Reid (Matthew Gray Gubler) will finally have his trial start, which might leave him behind bars for good. Meanwhile, an old victim returns to the show.

On the next episode of "Criminal Minds" season 12, titled "Unforgettable," Reid will soon be facing his trial. However, now that he remembered that he actually killed the doctor who had been supplying him with his mother's medicine, he might be staying behind bars for good.

Meanwhile, Rossi (Joe Mantegna) and his team will be working on a case that involves government personnel coincidentally having heart attacks.

"When several federal government employees, including a close friend of Walker's (Damon Gupton), succumb to symptoms of a heart attack, the BAU investigates. Also, Reid anxiously awaits his trial date," the episode listing on The Futon Critic reads.

The show has prepared another surprise for its viewers just before season 12 ends. Aside from Shemar Moore reprising his role of Derek Morgan, who will be providing valuable information to the BAU about Mr. Scratch, it has been confirmed that someone from the BAU's past will return in episode 20.

This returning character is Lindsey Vaughn, portrayed by Mantegna's daughter Gia, who was a victim of a kidnapping and who was saved by the team back in season 3 episode 12, "3rd Life."

TVLine interviewed executive producer Erica Messer about Vaughn's return. However, the showrunner remained tight-lipped about her appearance. Although, Messer does confirm that her return to the show already signifies a big spoiler for the episode.

However, Messer did share something that fans can look forward to. In terms of Reid's being convicted of murder, Messer shared that Mr. Scratch will be involved until the last episode of "Criminal Minds" season 12, hinting that there's still a chance for Reid's freedom.

"Criminal Minds" season 12 returns with episode 20 on Wednesday, April 26, at 9 p.m. EDT on CBS.