KILL 'EM ALLMulder is called in to serve as a profiler for a string of seemingly unconnected spree killings by different perpetrators. The only thing they have in common is that each killer also destroyed one or more electronic devices at the scene of the crime. Are the murderers the victims of some kind of electronically delivered mind control - and will Mulder be next?
- Afraid of Blood: Funsch is afraid of blood, and the subliminal messages that he receives play with this by goading him to attack a blood drive.
- Downer Ending: The spree killings are over after Mulder captures Funsch, but only because whoever is behind them decides to stop sending the subliminal messages that cause them, something that only Mulder knows because he receives a message of his own in the end ("All done. Bye bye.")
- Elvis Lives: Mulder's line:He's probably one of those people that thinks Elvis is dead.
- Haunted Technology: "Blood" has machines telling people to kill. Subverted — perhaps it was the government, using chemicals to cause mass paranoia in a controlled experiment and perhaps some people were actually sending the messages.
- Stock Episode Titles: 30 uses.
- Subliminal Seduction: The spree killers are driven to the deed by messages that appear on computer and digital screens, which play with their fears and insist to "kill 'em all" to provoke a survivalistic response.
- Suicide by Cop: Referred to by name as how most of the killers met their ends.
- Unusual Euphemism: This line on Funsch's sudden state of agitation:Bus Driver: Yeah, I picked him up. Drove four feet, then he went apewire.
- Why Did It Have to Be Snakes?: All the perpetrators are phobic and the exposure to insecticide heightened their already existing phobia to an unbearable level. One killer was claustrophobic (Why did it have to be a crowded elevator?), another one had a paranoia about rape (Why did it have to be a mechanic in a garage at night?) and the last one was Afraid of Blood (Why did it have to be blood?).