killer", who lived a double life, leading the police to not view him as a possible suspect until 30 years later.

John Wayne Gacy was responsible for 33 sadistic murders while maintaining the face of a model citizen.

Gwendolyn Graham and Cathy Wood were both nurses in Grand Rapids, Michigan who worked together in killing 5 elderly patients.

Samuel Collins killed his wife in Biddeford, Maine after discovering she was unfaithful throughout their ten years of marriage.

Dr. Stone met Latasha Pulliam at Dwight Correctional Center, who strangled her neighbor’s 6-year-old daughter.

On December 7, 2014, Investigation Discovery began airing new episodes with a new host, Dr. Kris Mohandie.

Stone researched hundreds of killers and their methods and motives to develop his hierarchy of "evil".

[4] In a follow-up book, The New Evil: Understanding the Emergence of Modern Violent Crime, published in 2019, he and co-author Dr. Gary Brucato, a clinical psychologist and researcher, break down the individual categories of the scale in detail.

[5] Neurologists, psychologists, and other forensic psychiatrists are interviewed on the show in an attempt to examine and profile the minds of notorious killers.