BTK—Bind, Torture, Kill. Every season, we end it with the scariest cases of all, the cases that could not be stopped no matter what you did. BTK, Dennis Rader, forever hanged how profilers and experts view serial killers. Before Rader, serial killers stuck to type, couldn’t quit, and eventually devolved getting caught. Not Rader. He was a family man, active church member, former soldier, married over 30 years, and a hard worker. He was the guy that you’d have over for beers and barbecue. Yet behind the scenes, Factor X (his name for his perverse desires and activities) drove him to sexual sadism. This case might keep you up at night.