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The new age of forensic neurology

Explaining and predicting the behaviour of serial killers


Nobody can argue that true crime has taken the media by storm in recent years. In 2021, the search to find Gabby Petito inflamed social media, with the r/gabbypetito subreddit having 120,000 members at its peak. Tiktok ‘psychics’ would amass millions of views by attempting to predict how the case would progress, with predictably terrible results. A small solace remains, however; the fact that increased media presence of murder cases increases the rate at which research into murderers is published. 

The increase in both research and media attention toward true crime continued through 2022, invigorated by the release of Monster: the Dahmer Story on Netflix, which was viewed on Netflix for over 1 billion hours by its user base. It could be argued that the popularity of this show and others depicting serial killers also increased the publication of research on the neurology of serial killers. 

The neurological basis of the serial killer refractory period

Dilly (2021) encompasses some very interesting correlational research into the neurological factors at play in the evocation of the serial killer refractory period. Following analysis of the refractory periods of ten American serial killers, a metaanalysis of prior research was performed to establish which prior theory most thoroughly explained the patterns derived. The American serial killers utilised in this investigation were:

  • The Golden State Killer, Joseph James DeAngelo.

  • Jeffrey Dahmer.

  • Ted Bundy.

  • John Wayne Gacy.

  • The Night Stalker, Richard Ramirez.

  • The BTK Killer, Dennis Rader.

  • The I-5 Killer, Randall Woodfield.

  • Son of Sam, David Berkowitz.

  • The Green River Killer, Gary Ridgway.

  • The Co-Ed Killer, Edmund Kemper III.

Theory no. 1

While this research is purely speculative due to the lack of real-time neurological imaging of the killers both during refractory periods and their murderous rampages, this research was demonstrated to lend credence to a prior theory proposed by Simkin and Roychowdhury (2014). This research, titled Stochastic Modelling of a Serial Killer, theorised based on their own collated data that the refractory period of serial killers functions identically to that of the refractory period of neurons. 

This theory is based upon the idea that murder precipitates the release of a powerful barrage of neurotransmitters, culminating in widespread neurological activation. In line with neurological refractory periods, it is believed that this extreme change in state of activation is followed by a period of time wherein another global activation event cannot occur.

Theory no. 2

Hamdi et al. (2022) delineates the extent to which the subject’s murderous impulses were derived from Fregoli syndrome, rather than his comorbid schizophrenia. This research elucidated how schizophrenic symptoms can synergise with symptoms of delusional identification syndromes (DIS) to create distinct behaviours and thought patterns that catalyse sufferers to engage in homicidal impulses. DIS include a range of disorders wherein sufferers experience issues identifying objects, people, places or events; Fregoli Syndrome is a DIS characterised by the delusional belief that people around the sufferer are familiar figures in disguise. 

The subject’s Fregoli Syndrome caused the degeneration of his trust of those around him, which quickly led to an increase in aggressive behaviours. The killer attacked each member of his family multiple times before undertaking his first homicide- excluding his father, whom reportedly ‘scared him very much’. Unsurprisingly then, his victim cohort of choice for murder were older men.

The neurobiological explanation of Fregoli Syndrome asserts that the impairment of facial identification, wherein cerebrocortical hyperactivity catalyses delusional identification of unfamiliar faces as familiar ones. 


Forensic neurology has been a key element in expanding the understanding of serial killers, with the research of Raine et al. (1997) popularising the use of neurology to answer the many questions posed by the existence of serial killers. Since Raine, Buchsbaum and LaCasse of the 1997 study first used brain scanning techniques to study and understand serial killers, the use of brain scanning techniques to study this population has become a near-perfect art, becoming ever more of a valid option for use both in understanding and predicting serial killer behaviour. In all likelihood, future innovations in forensic neurology research will continue to bring about positive change, reducing homicidal crime with the invention and use of different methods and systems to predict and stop the crimes before they happen.

Summarised from a full investigation.

By Aimee Wilson

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