A thorn in the side of the local authorities and gang task force for some time, the TSK was led by a man named Glen Hill, a.k.a. "The Reaper", and operated primarily out of his house in the suburbs. One late night in 2007, six members of the gang, including Glen, ambushed comic book artist and writer Jonny McHale and his pregnant girlfriend Vickie Wright while they were returning home from the store. Taunting the couple, Glen refuses the money Jonny offers and forces Vickie to agree to Jonny's marriage proposal, which the group had overheard seconds earlier. After harassing Vickie, the gang grabbed her and forced Jonny to watch as they gang-raped her, with Glen telling him, "You're not gonna wanna miss this", and ended up killing her. After killing Vickie, the group slashed Jonny across the stomach in an attempt to disembowel him and left him for dead. Miraculously, Jonny survived the attack but was rendered mentally unstable.
Six months after the attack, Jonny went after the TSK, brutally dismembering seven members apart with swords in the span of two weeks. A day after Jonny claimed his sixth and seventh victims, Glen holds a gathering at his house, which Jonny attacks, killing two guards outside before breaking in. Despite the group's attempt to defend itself, Jonny kills another four gang members before abducting Glen. Taken to a secluded location, Glen is then killed by Jonny, who gutted, partially dismembered, and decapitated him, telling Glen prior, "You're not gonna wanna miss this", which is the exact same thing Glen told him before making him watch the gang rape and kill Vickie. Whether or not the gang disbanded after Glen's death and Jonny's subsequent arrest is unknown, though it is possible that every single member of the gang is killed by Jonny, as it is not confirmed how many members there were in the gang. It is also never revealed if any of Jonny's fourteen victims were any of the five gang members besides Glen who were involved in Vickie's death.
- Glen "The Reaper" Hill (leader; deceased). Portrayed by Craig Gellis.
- Thirteen unnamed members (all deceased). All portrayed by uncredited actors.
- Presumably numerous unnamed others
The TSK used numbers to overwhelm victims and attacked using either small arms, blades, or their bare hands. When six of the gang members killed Vickie, they gang-raped her first (though it is unclear whether or not they meant to kill her, as it is possible she died as a result of internal bleeding from injuries inflicted during the attack), forcing Johnny to watch everything, and then slashed him across the stomach, nearly disemboweling him. The fact that they didn't succeed, however, suggests they were either interrupted or couldn't go through with the deed of gutting somebody. Given the name of the gang and leader Glen Hill's nickname "Reaper", it is likely that they killed other residents of Los Angeles, probably in gang-related killings on at least most occasions, and may have gang-raped other female citizens as well, though they may not have killed them. Any other crimes the gang may have been involved in, such as theft and drug dealing, are never mentioned.
As the investigation was focused on Jonny, no profile of the TSK was created by the BAU.
The 23rd Street Killers seems to be based on the 18th Street Gang. Both groups are similarly-named, violent street gangs that operate in Los Angeles, California, and are known to have committed several crimes such as murder.
Their attack on Vickie and Jonny also seems to be similar to the Death Angels's attack on their first victims, Richard and Quita Haugue. In both cases, a couple was attacked by a group of criminals, the woman was sexually assaulted before being killed, and the man was almost killed with a bladed weapon and left for dead, but survived. Coincidentally, both attacks also occurred in California.
- Presumably killed many unnamed civilians prior to and after the attack on Jonny and Vickie
- May 2007: Jonny McHale and Vickie Wright:
- Vickie Wright (gang-raped and tortured, killing her and her unborn child)
- Jonny McHale (attempted, but barely survived; was disemboweled)