The Chaos Killer is the alias/designation of a serial killer in Seattle. Major Lilywhite is coerced into becoming the Chaos Killer by Vaughn Du Clark. Vaughn wants all zombies destroyed in order to protect Max Rager's reputation, and is aware of Major's zombie-detecting ability. He hands Major a list of suspected zombies, found by searching for people with large purchases of hot sauce, hair dye and tanning sessions. Vaughn gives Major an ultimatum: track down any actual zombies on the list and kill them, or Vaughn will kill everyone on the list himself, starting with Liv Moore.
Major uses a tranquilizer gun equipped with horse tranquilizer darts, kidnaps the zombies, but hides them in a chest freezer instead of killing them. Vaughn eventually finds out and takes the frozen zombies back to the Max Rager lab to experiment on them.