Criminal Minds: Who Is Stephen Walker & How Did His Story End?

Like many long-running police procedurals, "Criminal Minds" is well known for having a constantly changing cast of main characters, with a wide variety of FBI special agents coming and going throughout the show's impressive 15-season run on CBS. Even with the cast's revolving door nature, not many main characters can boast that they lasted for less than a full season, as was the case with Stephen Walker (Damon Gupton). Walker first joined the FBI's Behavioral Analysis Unit in the Season 12 episode "Scarecrow," where he was introduced as an expert profiler who had transferred from the Behavioral Analysis Program. Specifically, Walker was recruited to help hunt down the serial killer by proxy known as "Mr. Scratch," aka Peter Lewis (Bodhi Elfman). Lewis was a Harvard graduate and certifiable genius who forced people to hallucinate a shadowy entity named "Mr. Scratch" and commit murder or die by suicide.

Having escaped from prison during the events of Season 11, Lewis spent much of Season 12 tormenting Walker and the rest of the BAU team that had put him in prison back in Season 10. Although Walker participates in several minor cases throughout this season, he most significantly contributes to the manhunt for "Mr. Scratch," working alongside the BAU to end the killer's reign of terror.

If you or someone you know is struggling or in crisis, help is available. Call or text 988 or chat 988lifeline.org.

Unfortunately for Stephen Walker, his involvement in the "Mr. Scratch" case directly led to his death in the "Criminal Minds" Season 12 two-part finale. Having tormented the BAU for practically the entire season, Peter Lewis makes a final attack on the team in the episode "Red Light" — posing as Penelope Garcia (Kirsten Vangness) to lure the group onto an abandoned back street.

Upon arriving at the street, the team hit a series of spike strips left by Lewis, and their now-immobile cars are rammed by a semi-truck. Everybody survives this crash except for Stephen Walker, whose neck snaps due to the whiplash. Having spent just 15 episodes with the BAU crew, Walker's death is incredibly shocking and tragic, though fortunately, his work on the "Mr. Scratch" case was not in vain.

In the Season 13 premiere, "Wheels Up," the team discovers that Walker made physical copies of all the evidence and research concerning the "Mr. Scratch" case — protecting those files from any hacking by the hyper-intelligent Peter Lewis. These documents were essential to David Rossi's (Joe Mantegna ) hunt for Peter and helped lead to Lewis' death later in the episode. Despite his short tenure with the BAU, Stephen Walker is given a hero's funeral at the end of the episode, attended by his wife, two children, and the rest of the team.