Gary Ridgway. America's most prolific serial killer. He claimed he murdered prostitutes because he thought he could get away with the crimes -- and for nearly two decades, Gary Ridgway, the Green River Killer, did. Ridgway murdered at least 49 people in and around Washington state's King County.
Robert K. Ressler is a former FBI agent and author. He played a significant role in the psychological profiling of violent offenders in the 1970s and is often credited with coining the English term "serial killer".
Dennis Lynn Rader is an American serial killer and one time mass murderer who murdered ten people in Sedgwick County, between 1974 and 1991. He was known as the BTK killer. "BTK" stands for "Bind, Torture, Kill", which was his infamous signature.