What factors develop psychopathic behaviours in serial killers?

Serial killers have been studied for many years, in which research aims to understand what causes people to commit repeated violent crimes. While every serial killer has a different background and life experience, research suggests that there is no single reason why someone becomes an offender. The Resource includes -What defines a serial killer? -Early Childhood Risk Factors -Serial Killer Behaviours -Role of Empathy in Prevention