The Mind of a Killer

I was recently watching the show Dexter, which is about the life of a serial killer who only kills other bad serial killers. It made me wonder about serial killers among of the psychopathic individuals and why they have disconnects with social interaction and emotion and what possible difference in the brain could be an explanation for this.

Many serial killers are sociopaths or psychopaths of some kind, which gives them the characteristics that can lead a person to become a killer. One way of studying such cases is through patients with Cluster B personality functions. People with Borderline Personality Disorder, Antisocial Personality Disorder, and Narcisstic Personality Disorder all display qualities that can be seen in many serial killers. In several cases patients have been shown to have reduced prefrontal gray matter, amygdala abnormalities, and asymmetric hippocampi areas. Some of these effects lead to symptoms such as emotional instability, anxiety, psychotic symptoms, paranoia and suspicion of others, impulsive aggression, lack of empathy, and low heart rate and levels of serotonin, which has lead to SSRI’s being used to try and treat some of these disorders.

In studies done on the brains of murders it was also found that they had significantly lower PFC activity and low orbital cortex activity. These can lead to less suppression of behaviors such as rage and violence as well as sexual behaviors, eating, and drinking. These neurological factors could also play a role in their lack of normal emotional attachment and sense of place with people and in society.

Studies have suggested that the vast majority of serial killer and psychopaths have several factors that result in their behaviors. Things such as genetics, childhood, and traumatic or abusive background all have a contributing role in these people.

Jim Fallon conducted a study looking at the brain characteristics that predisposed people to have violent and psychopathic tendencies. In the study he compared his own brain to several convicted murderers. To his surprise he found that he had many of the same brain patterns as the other killers. These included lack of activity in the limbic system, temporal lobes, and orbital cortex. Interestingly he also had many of the same genes connected with psychopathic behaviors. These qualities showed in his personality as his family pointed out. As he put it himself there are many things that he “knew were wrong, but didn’t care” which shows the emotional connection and attachment to things and people in life.

I found it interesting that he is not a serial killer however like many other people are with his same brain and gene structure. This shows how while brain structure can be a precursor for something, it does not necessarily seal your fate. In class we talked about how brain function can predict behavior, but the brain’s plasticity through ones life can cause different outcomes, which I thought fit well with Fallon’s story.

This video shows some of Fallon’s finding when looking at scans of his own brain.

brain scan

This image shows the difference in brain activity between a normal person (left) and a serial killer (right). It can clearly be seen that the normal subject has a great deal more activity in the PFC than the serial killer, which perhaps equates for the tendencies to be emotionally detached from others and unable of empathy.


8 thoughts on “The Mind of a Killer

  1. I thought the fact that Jim Fallon commented that things with him “were wrong, but [he] didn’t care” was interesting because it seemed almost contradictory. In hindsight, one could argue that he cared enough to look deeper into the matter. Could it be that he was trying to fit himself into a category of having psychopathic tendencies because he made this discovery about his brain? It’s also shocking how childhood has such a big effect in one’s development throughout lifespan.


  2. This was a really interesting article. We always hear that psychopaths and people with mental disorders having different brain chemistry and it will be interesting to see if we can eventually figure out the underlying causes. I wonder if, knowing the PFC is less active in serial killers, doctors could identify people who are likely to develop certain psychopathic tendencies and have some sort of neurological intervention. It would be revolutionary if doctors could somehow make the PFC more active and thus decrease the likelihood that possible psychopaths would develop into serial killers.


  3. This is a fascinating topic. I’m taking a Genes and Evolution class right now, and we’ve been discussing the importance of regulating gene expression. As the video mentioned, just because you have the “warrior gene” doesn’t guarantee you will be violent, since are many cis-regulatory elements (transcription factors, enhancers, inhibitors) that determine when and for how long a gene is expressed. Although Jim might have exhibited predispositions to psychopathy by scaring his son or experiencing apathy, his brain was probably expressing the worrisome genes in much lower concentrations than that of a serial killer’s. An interesting investigation would be a correlative study between the “serial killer PET scan” and the expression (not just presence) of “serial killer genes.”


  4. This post reminds me of my Personality Psychology class and a study we just recently read. It was very similar in that they were looking at high and low activities of the gene (MAOA), with low activity usually being associated with violence. They were comparing low and high MAOA with no maltreatment, probable maltreatment and severe maltreatment and how much more violent (convicted of violent offenses, conduct disorder etc.) they were in these conditions with that gene. The people who had low MAOA activity and who were severely maltreated had huge tendencies towards violence, it was almost double that of people who were severely maltreated and had high activity of MAOA. But the people who had this same gene and were not abused were not that violent. I think it really does show just like these studies mentioned in the blog post that the environment plays a huge role in conjunction with genes that one was born with. I think this is a great example of how nature and nurture work together and how each part really effects a person just like Jim Fallon’s studies.


  5. I really like this article because I often tend to have an interest in watching shows about murderers and psychopaths like Criminal Minds and Law & Order. I think your point about the lower PFC activity is very interesting to think about in relation to the nature and nurture debate. While these lower levels can indicate an increase in behaviors like rage and violence, which can influence their role in a “normal” society. It is also interesting to think about how their childhood development or overall experiences shaped these aspects of their brain – or if this is something they were actually born with.


  6. I’ve always found it interesting that our society is often fascinated by the minds and thoughts of serial killers. The media has expanded its coverage on the topic with shows like Dexter, Castle, and Bones, all shows I avidly follow. As someone who has always been interested in this topic, I find myself reading up on case studies and watching documentaries concerning serial killers, their confessions, and their individual processes of action. Thus, I find it very interesting that Jim Fallon found such profound similarities between his own brain and those of his subjects. Could it be that many of us are fascinated by the phenomenon because we ourselves have slight neurological inclinations toward this behavior? Perhaps it is similar to what Jackie said that Fallon was trying to fit himself into such a category because of his known similarities, or perhaps it is not surprising at all that those most interested in the idea have an interest because they have a predisposition. I should clarify that I am in no way suggesting that all those fascinated by the idea have the mental inclination to become one themselves (everyone loves a good mystery, of course) but that our own neurological foundation may just be what drives many to the phenomenon to begin with.


  7. The first thing that struck me about this article was that psychopathic and violent tendencies are not only the results of personality, but also genetic and physical differences in the brain. The author also points out that the recipe for a serial killer is often a combination of nature and nurture – a trend we have come to accept as a major theme in psychology. While brain differences certainly play a role, the author states that many serial killers have childhoods filled with trauma and abuse, which only exacerbate their genetic predisposition. In society, we often tend to look at these individuals with disdain – believing that they are fully responsible for their actions. While I am no judge, and I’m not sure on my stance regarding the role of brain disfunction in murder (pleading insanity, for instance), I do think it’s important for people to remember that some factors exist beyond the control of these individuals.
    The article ends by discussing the work of Jim Fallon, who conducted a study to observe differences in brain characteristics in psychopathic individuals. His comparison was his own brain, but instead of finding large differences, his results showed very similar brain patterns. It was also noted that Fallon, while not a killer, was somewhat emotionally detached, and had a childhood far from idyllic. These similarities in both upbringing, personality, and genetics, however, did not motivate him to become a serial killer. The author claims that these findings lead to the conclusion that brain plasticity and ongoing life events also play a significant role in the shaping of an individual. I would be curious to know about another explanation – that perhaps that individuals are indeed born with souls – alterable neither by physical difference nor upbringing.


  8. This article stood out to me because of the topic choice of serials killers and how their brains work. I’ve always been curious as to why serial killers do what they do, and throughout my biographical readings a good majority of the killers had traumatic childhoods. It’s interesting to see the brain activity of a serial killer and how it compares to a normal person, and also how their brains were shaped by their childhoods. What I wonder is, as infants, did the serial killers have all the brain and genetic markings of a killer and their childhoods made those markings more dominant? Also, what is it about traumatic childhoods that decreases the activity of the PFC?


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