"We believe that to understand the why of serial killers, one has to first accept the existence of the unconscious mind: that things are going on in it constantly and that it is capable of controlling behavior.
When a child is abused in one way or another by parents, the anger and terror he or she feels is hidden in the unconscious, which becomes like a seething cauldron, and the child starts looking for ways to deal with the terrifying feelings emerging from it. Someone in the family, usually the mother or father, has clearly shown the child that he or she has no value except perhaps as a sex object or someone to hurt. A terrible fear builds up in the child's unconscious that results from feeling constantly under threat, so the child starts to formulate fantasies of being all-powerful, controlling, and able to handle whatever comes his or her way. Then, the child creates symbolic scenarios in which he or she is dominant or acts out, first by showing mastery over animals by abusing them, and sometimes over structures while burning them down. This manifests in adulthood as a powerful sex drive and the abuse of the women or children in the person's life.
While all of us are subject to some stress in our childhoods from our parents, the stress we are talking about here is horrendous, and the reaction of the child is equally so. Ken Bianchi's mother held his hand over a stove flame to punish him. Edmond Kemper's parents made him kill hid pet chicken and forced him to eat it, tears streaming down his face, for dinner.
At some point in serial killers development- usually when they’re in their 20's- the fantasies or the cruelty to animals is no longer enough to satisfy their murderous rages, and their compulsion is satisfied by nothing less than killing people. We believe that serial killers are unconsciously terrified of and furious with people because of their own childhood and that they kill to temporarily alleviate that terror. And "temporarily" is a key consideration. At the risk of redundancy, the act of dominance, of killing, must be done over and over again to support the serial killer's delusion that he or she is all powerful, to reassert superiority.”