The mind of a killer seems like a sinister labyrinth, its dark, twisted recesses pulsating with primal, animalistic bloodlust. Are killers born with a perverse craving for inflicting unspeakable suffering upon others, or do these horrific tendencies develop with time? While the answer to this question is uncertain, evidence is now suggesting that a killer's brain can, indeed, differ from the brain of the average person.
Many researchers have linked brain defects and injuries to uncontrolled aggression. While some of these injuries were accidental, some were inflicted during childhood beatings. David Berkowitz, Ken Bianchi, John Gacy and Carl Panzram are among many serial killers who endured head injuries or infections.
When various parts of the brain are traumatized, deviant behavior can result. The hypothalamus is the section of the brain that controls hormones and emotions. Since the sexual and aggressive centers are adjacent to each other within the hypothalamus, its damage may result in sexual instinct and violence intertwining for lust-driven murders.
The limbic brain is connected with emotion and motivation. If it is injured, an individual can lose control of fear and rage. Serial killers are often referred to as "cold-blooded," likening them to reptiles, which also lack the limbic part of their brain.
The temporal lobe of the brain is a part that's very vulnerable to harm, since it's located where the skull bone is the thinnest. If this lobe is damaged, the injury can engender violent, hair-trigger reactions and escalated aggression. When he was a child, Ken Bianchi tumbled from a jungle gym and landed on the back of his head. The injury led to epileptic seizures, and quite possibly to his future vicious behavior.
The prefrontal cortex, the part of the brain associated with long-term planning and judgment, is thought to function improperly in psychopaths. Paleopsychologists also contend that the primitive brain of killers prevails over the "higher" brain, and reason and compassion are overridden by lust and aggression. According to a study by Pavlos Hatzitaskos, a vast amount of death row inmates suffer from severe head trauma, and 70% of patients with brain injuries develop aggressive behavior.
German neurologist Dr. Gerhard Roth claims to have discovered where evil dwells in the brains of killers. He states that this murderous instinct is located in the brain's central lobe, and appears as a dark mass in X-rays. While showing violent offenders films containing brutality, Roth measured their brain waves. In areas that register compassion and sadness in the average brain, nothing happened in the criminals' brains. Roth discovered the dark mass in the brain scans of all criminals with violent records. He also purported that substances such as serotonin – a "feel-good" chemical produced by the brain – are acting ineffectively in the part of the brain harboring this dark mass.
Other evidence gleaned by researchers at King's College London's Institute of Psychiatry shows that psychopaths' brains may be structurally different from the average person's brain – that they may literally be born to kill. Scans by scientists revealed that killers have less gray matter in areas of the brain necessary for understanding others, empathizing with them, responding to fear and distress, remorse, and embarrassment or guilt. Killers' brains are not activated by thoughts of moral behavior. Because of their brains' inherent structural abnormality, behavioral treatments are rendered useless.
Serial killers' brain neurons have also been found to fire differently than those in the average person's brain. Mathematicians Mikhail Simkin and Vwani Roychowdhury at UCLA analyzed the pattern of serial killer, Andrei Chikatilo, who murdered 56 victims over the course of 12 years. They concluded that it matched the pattern they'd predicted for neuron firing in his brain – that he felt compelled to kill after his neural excitation crossed a threshold for a specific period.
The frontal lobe of a killer's brain was also of great interest to Adrian Raine of USC and Monte Buchsbaum, now at Mount Sinai School of Medicine in New York. After conducting brain scans on 25 convicted killers, they discovered abnormalities in the frontal lobes – the front portions of the brain. In the average person's brain, the frontal lobes are highly active – in a murderer's brain these lobes are inactive. Why is this important? Because this area of the brain is integral to planning, organizing – and impulse control, which killers have in very short supply.
Some people are natural born killers whose brains are very different than the average person's – and whose brains command them to kill. Often, murderers with abnormal brains don't know why they kill – and even more chilling, they can't guarantee that, if they're released from custody, they could stop themselves from killing again.