|“||I don't kill because I don't have to.||”|
Very little is known about Cullen, including why he began his attacks in Tempe, Arizona, though Reid would later mention that Cullen was an injustice collector, which could indicate revenge as a motive. Cullen's crimes soon got him the moniker of "The Crimson King" and caught the attention of the FBI Fugitive Task Force in 2013, who tasked Luke Alvez and Phil Brooks with apprehending Cullen. During the manhunt, Phil went undercover in order to lure Cullen out into the open. Though the operation was a success and Cullen was captured, he had managed to torture Phil by disemboweling him, telling him not to flinch beforehand. This severely traumatized Alvez, who was Phil's partner. On September 28, 2016, the prison that held Cullen was attacked by a group of anarchists as part of a larger terrorist attack. Though the attack was foiled, Cullen managed to escape in the chaos. While on the run, he was tracked down by another escapee, Peter Lewis, who captured him.
The Crimson King
While Cullen was held captive by Peter, he was drugged and forced to lose his memory of who he is. Peter then leaves Cullen alone with his first drugged victim, Brian Phillips, who was hypnotized by Peter to believe he is Cullen. To this end, Brian attempts to carve "Impostor" into Cullen's stomach after being told by Peter that Cullen thinks he is the Crimson King. After Brian is arrested by the BAU, Cullen thanks Alvez and Reid for saving him as the latter handcuffs him. Alvez is enraged by Cullen's behavior, but Reid realizes that Peter drugged him and that he doesn't remember who he is. Alvez doesn't believe it, so he attempts to remind Cullen about their encounter three years prior, and demands him to tell him his name and his partner's name. However, these efforts are unsuccessful, and Cullen is led away by Reid. He was either institutionalized due to his memory loss or put back in prison, as Alvez remarked that the drug's effect could be temporary.
Cullen abducted his victims in an unspecified manner, held them captive for an undetermined amount of time, and tortured them severely. His signature was carving messages into his victims' bodies: his male victims would have messages carved into their stomachs, while his female victims had messages carved into their foreheads. Afterwards, he released them into the wilderness with their arms chained to an arm-stretcher and left them to die from exposure. Though his exact victimology was never elaborated on, it can be assumed that he selected his targets beforehand as he was said to be an injustice collector.
No official profile was made by the BAU, though Reid called him an "injustice collector"-type killer, suggesting his stressor was some school-related event that happened either to him or someone close to him.
A Twitter post confirmed that Cullen was inspired, in part, by David Parker Ray, a.k.a. "The Toy Box Killer", a serial rapist and suspected serial killer. Both were serial offenders who operated in Arizona and tortured their victims. While Ray wasn't known to have forcibly engaged in BDSM with his victims, his homemade torture chamber was found to have a number of BDSM items, including spreader bars; this may have been referenced through Cullen chaining his victims to arm stretchers.
- Caleb Esperson (carved "Fail" into his stomach)
- Lindsey Dreifort (carved "Drone" into her forehead)
- Wade (carved "Disgust" into his stomach")
- Phil Brooks (Alvez's partner; tortured by disembowelment only; apparently did not carve a message into his stomach)
- Cullen is partially similar to Season Three serial killer Brian Matloff, in the sense that both suffered from amnesia and had no recollection of their old crimes after being captured by the BAU, albeit for different reasons. Both also managed to escape from police custody for a brief period of time, resulting in manhunts for them.
- Season Eleven
- The Storm (mentioned)
- Season Twelve
- Season Thirteen
- Dust and Bones (mentioned)