Dennis Rader, aka the BTK Killer
First appearance: Episode 1
Dennis Rader, or the BTK ("bind, torture, kill") murderer, frames the series but never comes in contact with the Behavioral Science Unit. Why? Because Rader, who killed 10 people throughout Wichita, KS, from 1974 to 1991, wasn't caught until 2005. We just see shots of him sprinkled throughout the series acting suspiciously. In episode two, Bill does talk with one of his surviving victims, Kevin Bright.