What draws mankind toward the darkest corners of evil? Killers who feed on human beings are analyzed and ranked on the Scale of Evil.

Is it possible for an ax murderer and a career criminal to find redemption? Where do they place on the Scale of Evil?

Statistically women are far less common to commit acts of brutality, but their motives and methods can be every bit as cruel. How do they measure on the Scale of Evil?

Sometimes the most heinous acts are committed by those we trust most. Dr. Kris Mohandie ranks a notorious Black Widow after the mysterious murder of husband number three.

When a domineering ex-military man fears losing control over his family, he commits unspeakable acts of brutality. How do controlling killers rank on the Scale of Evil?

Some of the world's most notorious killers include men who fail to control their darkest impulses. Where do sexual predators rank on the Scale of Evil?

For killers who attempt to mask their crimes, deception itself is just another weapon. Where do diabolical schemers land on the Scale of Evil?

Many murderers possess narcissistic tendencies, but there is a unique group who are pathologically and dangerously self-obsessed. Where do they rank on the Scale of Evil?

Retired police investigator Jim Horton tells Phelps how he betrayed the confidence of a thief- turned-informant in order to bring a killer to justice.

Law Enforcement Agent Dennis Haley recounts the night he spent in a hotel room with serial killer, Mark Riebe.

A small-town detective describes a twisted murder investigation that spans multiple states involving a stolen identity.

Whenever Belle Gunness has guests at her farm, they disappear. Authorities quickly uncover a horrifying secret in Belle's barn - a secret that leaves the whole town speechless.

Claire and Dora Williamson just want to be healthy and happy. When they check into the luxury spa, Wilderness Heights, they find themselves in a terrifying situation with no escape.

Ed Gein's only ambition in life is to please his Godfearing mother, Augusta. But when Augusta passes away, Ed finds a frightening way to cope with the sudden loss.

Grady "Lobster Boy" Stiles loves all of the attention he gets at his circus sideshow act. When he ends up dead, Detectives learn that the beloved entertainer actually had many, many enemies.

Ken Parks had it all: a great job, happy wife, and a loving family. When he develops a secret gambling addiction, his demeanor changes. Then, his peculiar behavior, quickly warps into murderous behavior.