The Mind of a Killer

What drives people to commit murder? I wrestled with the question as a law enforcement officer, and now continue to do so as a crime writer. 

According to the CDC, over 26,000 homicides occurred in the US in 2022. It’s not the highest year on record, which was 1991, but the rate has been trending upward lately. As opposed to the fictional detectives we all love, real-life homicide investigators usually attribute intentional killings to one of three motives:

• Drugs – including turf battles, rip-offs gone bad, and binge-fueled violence.
• Sex – including human trafficking, jealous rages, and any other fatal violence involving an intimate relationship.
• Money – during the commission of robbery, a burglary, or involving life insurance fraud, and murder-for-hire.

Very few homicides are the work of psychopaths and/or serial killers, which are defined by the FBI as killing at least three people over a period of time with a cooling-off period in between. Why then, are so many of us fascinated by those rarest of murderers? 

I believe it’s because those individuals look, act, and talk like everyone else—superficially, at least. They blend into society, but they are wolves in sheep’s clothing…or is it more accurate to say they are sharks?

A criminal profiler teamed up with marine biologists to compare the predatory behavior of sharks and serial killers. [1] Turns out their hunting patterns and techniques had several disturbing traits in common:

• Stalking their victims – they do not strike at random.
• Premeditation – they lurk out of sight, observing from a distance.
• Prey selection – preferring those who are young, alone, or vulnerable.
• Attack style – ambush by striking when no one else is around.
• Geographic territory – operating within a set area (there is a whole field of criminal psychology devoted to “geographic profiling” for this reason).

So, who are these sharks swimming among us? Many of them can be classified as sufferers of antisocial personality disorder, commonly called psychopaths, who share these classic traits: [2]

• Tendency to manipulate others
• Superficial charm
• Abnormal egocentricity
• Lack of empathy exhibited as guiltlessness 
• Impulsiveness and aggression

Are psychopathic killers unaware they’re acting in a morally reprehensible way, or do they know right from wrong and just don’t care? To find out, a group of scientists provided moral dilemmas while conducting brain scans of serial killers and found: [3]

• Impaired connectivity between the prefrontal cortex (executive function) and the amygdala (emotional responses: fear, happiness, anxiety, anger)
• Impaired connection between the prefrontal cortex and the anterior temporal lobe (learning and retaining new information)
• Impaired connection between the prefrontal cortex and the medial parietal cortex (memory recall, visual processing, spontaneous thought)

When exposed to images or recordings of murders these individuals had committed, they remained aloof to cries of distress or anguish by their victims and lacked any remorse or guilt over what they did.

They concluded that psychopathic serial killers know what they did was wrong but [4] were not deterred by negative consequences such as going to prison or causing harm or distress to others.

In another study, a neurologist analyzed the brains of 70 psychopathic killers. [5] He found several structural differences between their brains and those of neurotypical subjects, including:

• Damage to the orbital cortex (directly above the eyes)
• Damage to the interior part of the temporal lobe
• Other sorts of brain damage varying by individual

So, is nature or nurture to blame? Dr. Fallon concluded the answer is both. An inborn predisposition toward violent psychopathic behavior may remain dormant but can be activated when a young child is exposed to major trauma, such as severe abuse, war, or disaster, before puberty while the brain is still forming.

I use my law enforcement background to create realistic criminals. One of the resources I recommend is Mindhunter, [6] which provides both an insider’s view of how law enforcement hunts serial killers and the psychology behind how these predators think—in their own words—garnered from prison interviews.

Here’s my advice for writing realistic fictional murderers. I’ve separated them into two categories:

1. Mostly neurotypical, but killed for one of the three main motives listed at the beginning of this article:

• • Remember that they are the hero of their own story. No one thinks they’re a terrible person.
  • They will mitigate their own guilt by making excuses, blaming the victim, blaming society, or saying they had no choice.

1. A psychopathic serial killer, can be depicted as:

• • Charming – when it suits their purpose.
  • Having a flat affect – when they don’t feel the need to charm others.
  • Smart – can be high IQ, or simply highly cunning—even if uneducated.
  • A good actor – they’ve learned to portray emotions they don’t feel.
  • Manipulative – their superpower; gaslighting, bargaining, and lying.
  • Deeply insecure – their kryptonite; this is well-hidden; most of their actions are to provide a sense of superiority/power/dominance they lack.

Sources:

[1] L. Miller, “Serial Killers: Subtypes, patterns, and motives,” Aggression and Violent Behavior, pp. 1 – 11, 2014, Volume 19, Issue 1.

[2] P. V. Wlassoff, “Neuroscience and Neurology,” 18 May 2015. [Online]. Available: https://brainblogger.com/2015/05/18/decoding-the-neural-pathway-from-psychopathy-to-serial-murder/.

[3] M. L. a. P. Ciaramelli, “Selective deficit in personal moral judgment following damage to ventromedial prefrontal cortex,” Social Cognitive and Affective Neuroscience, Volume 2, Issue 2, pp. 84 – 92, 2007.

[4] L. . Miller, “Serial killers: I. Subtypes, patterns, and motives.,” Aggression and Violent Behavior, vol. 19, no. 1, pp. 1-11, 2014.

[5] J. Fallon, Professor, Univ of CA: Portfolio, 2014.

[6] J. E. a. O. M. Douglas, Mindhunter: Inside the FBI’s Elite Serial Crime Unit, Quantico, VA: Gallery Books, 2017.

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