The Scale of Evil
In 2010, forensic psychologist and Columbia University professor Michael Stone, came up with a scale inspired in Dante’s circles of hell to classify criminals from the 20th century.
The scale goes from 1 to 22 and is divided in three cathegories: impulsive murderers, semi-psychopaths (meaning they lack the extreme characteristics of them, but can be psychotic) and finally, psychopaths who are manipulative, cunning and show no remorse.
Number 1 in the scale is out of these clasifications, since it’s “justified murder”, or self defense, and not regarded as “evil”.
2. Jealous lovers, non-psychopathic, who commit crimes in the heat of passion.
3. Willing companions of killers.
4. Provocative “self defense”, meaning someone who provokes an attack and then kills to protect themselves.
5. Desperate measures, traumatized people that later show genuine remorse.
6. Hot heads, who act in an “impetuous moment” without marked psychopathic features. Stone puts infamous cannibal Issei Sagawa here.
7. Narcissists, possessive but without psychopathic traits, they kill out of jealousy.
8. Fit of rage, they kill when it’s ignited. Stone puts Charles Whitman, the Texas Tower shooter, here.
9. Jealous Lovers, with psychopathic traits.
10. “In the way” killers, not fully psychopathic. They murder people who are an obstacle, like witnesses or family members.
11. “In the way” psychopaths. Same as above, but with more coldness.
13. Inadequate and rageful. They are angry because of the shortcomings they’ve experienced in life, show some psychopatic impulses. Example: Eric Harris.
14. Schemers. Self-sentered, they plan their crimes and won’t stop at nothing.
16. Vicious psychopaths, who kill in gruesome ways.
18. Torturing murderers, although they don’t prolong it. Murder is their primary motivation. Example: Gary Ridgeway.
20. Murdering torturers, they can be considered legally insane and are motivated mainly by their desire to torture. Example: Joseph Kallinger.
21. Pure torturers. They enjoy torturing their victims to the extreme, but not necessarily murder them. Example: Cameron Hooker.
22. Psychopathic torture-murderers. They inflict prolonged pain before killing their victims. It’s a trait seen in many male serial killers. Example: Jeffrey Dahmer.
More about it here