Studies suggest that serial killers’ brains can be different—but not in the way that guarantees someone will become a killer. Research involving brain scans of murderers, including serial killers, has revealed differences in the structure and function of certain brain regions, especially those linked to emotion, decision-making, and impulse control. For example, many of these individuals show reduced gray matter in areas like the prefrontal cortex and the orbitofrontal cortex—parts of the brain that help us regulate emotions, control impulses, and make socially appropriate decisions.
Other studies have found abnormalities in the amygdala, the part of the brain that helps process emotions like fear and aggression. This might explain why some killers display a disturbing lack of empathy or remorse. Functional imaging, like PET scans, has also shown unusual brain activity in violent offenders, especially in areas involved in emotional responses and self-control. One large study involving over 800 incarcerated men found a noticeable difference in brain structure between murderers and non-violent inmates.
But here’s where it gets complicated: just because someone’s brain looks or works differently doesn’t mean they’re destined for violence. Many people with similar brain patterns never commit crimes at all. That’s why scientists emphasize that brain differences might increase the risk, but they’re not a guarantee. Environment, trauma, upbringing, and even genetics all play crucial roles, too. So, while serial killers’ brains often do look different on a scan, those differences are just one piece of a much larger, darker puzzle.
