Are all serial killers considered sadistic?
Generally, I would say no. Most serial killers are Sociopaths (They have Anti Social Personality Disorder) however some of them who may have been severally abused (Abuse at a young age is thought to cause or at least contribute to ASPD) in a sadistic way may in turn “replay” their abuse through their victims. They may do this because as a small child you are helpless, and once they reach an age where they can control others, they want a feeling of power and control. Many of them also abuse/kill animals when they are younger before they start killing humans.
