How the Mind of a Serial Killer Works: How We Differ from Them
We often call the most terrifying criminals—such as serial or mass murderers—“inhuman.” While this may seem like a metaphor, there’s an underlying suggestion of biological difference. Something about these criminals seems fundamentally different, almost non-human. The question of whether there are born killers, and whether it’s possible to identify a potential criminal by physiological traits, has intrigued people since the 18th and 19th centuries, when emerging scientific ideas competed with exotic misconceptions.
Reading the Skull
Austrian physician Franz Joseph Gall (1758–1828) created the theory of phrenology. Gall believed he could determine which parts of the brain were responsible for various mental abilities, and that these abilities were reflected in the shape of the skull. In other words, by examining a skull, one could supposedly tell if someone was a potential Mozart or a potential Jack the Ripper. The skull was considered even more important than the brain itself. Even in his own time, Gall was a controversial figure, and his theories and fascination with skulls were criticized. However, Gall did have the brilliant insight that intelligence is linked to the frontal lobe of the brain. Phrenology itself, though, failed as a method for identifying socially dangerous individuals.
Compared to a Psychopath
In the second half of the 19th century, another controversial figure, Italian psychiatrist Cesare Lombroso (1835–1909), took up the cause. He believed that criminal tendencies were physiologically predetermined and looked for evidence in physical traits: sloping foreheads, large ears, facial and cranial asymmetry, prognathism (protruding jaws), and unusually long arms. Lombroso thought these features indicated an underdeveloped, atavistic person, closer to wild primates. Such people, he believed, were destined to be sociopaths and criminals. Lombroso’s ideas and methods were also criticized, but at the time, they weren’t considered especially exotic or marginal. His contemporary, Francis Galton, a relative of Darwin, developed the theory of “eugenics,” which advocated for artificial selection among humans, similar to animal breeding. Only people with good physical and intellectual traits should reproduce, while those deemed “defective” should be excluded. These were just theories until the Nazis came to power in Germany and began to put such ideas into practice. After the defeat of Nazi Germany and the exposure of their crimes, discussions of the biological basis of antisocial behavior became taboo in Europe. The prevailing view became that criminals are shaped by their social environment, troubled families, and childhood trauma.
Prison Science
Meanwhile, since the days of Gall and Lombroso, the life sciences have advanced greatly. We’ve learned about genes, and neurophysiology has made significant progress. The question of whether a predisposition to horrific crimes is “wired” into our physiology inevitably resurfaced.
In recent decades, the term “neurocriminology” has emerged, describing a subdiscipline focused on studying brain structures that could serve as the biological basis for antisocial behavior. Special attention is given to the causes of psychopathy—a mental anomaly that deprives a person of empathy and gives them traits like cynicism and cunning. This disorder is common among serial killers, for whom taking a life is not a serious moral issue.
Modern researchers, like Lombroso before them, often have to go to prison—not to serve time, but to study the desired subjects up close. One of the founders of neurocriminology, British scientist Adrian Raine, spent four years in two maximum-security prisons as a psychologist in the early 1980s. The ideas he developed there were too controversial for tolerant England, so in 1987 he moved to the United States, where research into the biological predisposition to crime was more accepted—and where there was more material to study, given the higher crime rates and larger prison population.
Falling from a Cherry Tree
Studying the physiological causes of psychopathy is crucial for understanding serial killers and other villains, but not all psychopaths are born killers, and not all killers are psychopaths. Some studies show that among repeat murderers, there are people with other types of mental disorders, such as borderline personality disorder. Also, if we talk about damage to the frontal lobes as a factor in developing an antisocial personality, this damage doesn’t have to be congenital. For example, serial killer Albert Fish, known as the “Brooklyn Vampire,” was a normal boy until he fell from a cherry tree at age seven and suffered a head injury. Afterward, he began experiencing headaches and showing signs of aggression. At 20, he killed and ate his first victim.
In America, Raine was among the first to use modern medical technology, such as positron emission tomography (PET), to study the brains of criminals. He selected two groups: one of 41 convicted murderers and another of 41 law-abiding citizens. PET scans showed significant differences between the brains of prisoners and free citizens, especially in metabolic activity. Structurally, the criminal brain showed underdevelopment of the prefrontal cortex, which is responsible for social interaction. These features can result in poor control over the limbic system, which generates basic emotions like anger and rage, as well as a lack of self-control and a tendency toward risk-taking. Aren’t these the traits of a criminal personality?
Brain Explosion
Similar studies have been conducted at other research centers, such as the University of Wisconsin–Madison. A 2011 study presented results from brain scans of psychopathic criminals. The data showed that psychopathy is caused by a weakened connection between the prefrontal cortex and the amygdala—a part of the limbic system. As a result, negative signals from the prefrontal cortex don’t trigger strong emotions when processed by the amygdala. This leads to a lack of compassion and guilt, which are characteristic of psychopathic personalities. Moreover, scientific studies have shown a link between criminal behavior and certain genes. In 2019, Professor Jari Tiihonen of the Karolinska Institute in Stockholm announced that he had found the CDH13 and MAOA alleles—the so-called “warrior gene”—in the genomes of people who had committed multiple violent crimes. The MAOA gene is responsible for producing the reward hormone dopamine, but in its mutated A variant, it can be very dangerous. People with this gene experience a sharp increase in dopamine production when consuming alcohol or drugs, which “explodes the brain” and leads to uncontrollable aggression. The CDH13 gene also negatively affects behavior and is linked to attention deficit hyperactivity disorder (ADHD).
The Unfulfilled Psychopath
Does all this prove Lombroso and the eugenicists right? Of course not. Even if a biological predisposition to antisocial behavior exists, it’s only one factor in personality development. Other factors include social environment, family situation, stress, trauma, and more. The story of American neurophysiologist James Fallon is interesting in this context. He spent years searching for the causes of psychopathy by studying brain scans of various antisocial types. His life changed after a conversation with his elderly mother, who told him about his father’s family tree. It turned out that at least seven murderers were among his ancestors dating back to the 17th century. Fallon then scanned his own brain and found that it had all the hallmarks of a hardened psychopath: the same underdeveloped prefrontal cortex and weak connection to the amygdala. The scan looked very similar to that of a serial killer. Fallon recalled that in his youth, his predisposition to psychopathy may have shown itself—he was a real daredevil, making homemade bombs, stealing cars, organizing risky adventures, and involving his friends. He was narcissistic and devilishly self-confident. But as he grew older, James Fallon became a quiet family man and a successful neurophysiologist. So, there is no inevitability.
Science or Freedom?
Neurocriminological research raises a number of moral, ethical, and even political questions. If certain genetic or neurophysiological traits are definitively declared risk factors, how should society and the state treat such individuals? Will these traits become a kind of stigma that, in the age of information, will follow a person for life and prevent them from pursuing their desired career? Should people with worrying predispositions be forced to participate in personality correction programs to suppress what has become an undesirable gift of nature? From the perspective of individual rights, how will attempts to “get into someone’s head” for public safety reasons be viewed? It’s hard to predict the answers to these questions, but it’s unlikely that the solution lies in bans or suppressing scientific progress in this area. We will always be interested in who we are and why.