The Mass Shooter and His Mental Functioning


A tripartite dimensional approach may be used to better understand the mental functioning of those who commit mass violence.

Mental functioning spectrum

Table. Mental functioning spectrum

Follow-up to Mass Shooters and the Psychopathology Spectrum, by Ronald W. Pies, MD.

Core article concept: schizophrenia


In search of a silver lining to the recent focus on “mental illness” as a primary antecedent to mass shootings, we are hopeful that a much-needed dialogue about mental health might be stimulated. Characterizing mental illness in a way that is demystifying and readily understandable is challenging for mental health professionals, let alone the lay public. Nevertheless, we go in search of a place to begin our dialogue, and broad concepts seem better suited for a starting point than do highly granular views. In this vein, we would like to offer a dimensional approach that is now receiving vigorous attention-a single dimension view of mental health.1 Although this is not a new concept, there has been a burst of research around dimensionality and mental illness, leading some to assert it may be “superior” in terms of future scientific study.2

Dimensional approaches vary, but one approach aggregates psychiatric symptoms into three domains along a single dimension of psychopathology: 1) internalizing, 2) externalizing, and 3) psychotic experience. This tripartite dimensional approach is appealing-not only because of the robust research supporting it, but also because it can be used as an overarching structure by which much of mental functioning can be understood. The Table shows this dimensional approach, along with observations on how key psychological concepts cluster along what we should like to call a “spectrum of mental functioning.” This model is essentially old wine in a new bottle. Freud originally used this terminology in his paper, “The Loss of Reality in Neurosis and Psychosis.”3 Freud wrote that “neurosis does not disavow the reality, it only ignores it; psychosis disavows it and tries to replace it.”3 Thus, along our spectrum of mental functioning, Freud might point out that in each domain there is loss of reality-it is simply a matter a matter of how much. For the psychotic domain, the psychosis puts itself forth to replace reality entirely. In contrast, in the internalizing domain, only a piece of reality is shielded behind the relevant defense mechanism.

Such a dimensional approach may be used to measure an individual’s vulnerability to different types of mental disorder, comorbidity among disorders, persistence of disorders and severity of symptoms. Another way of viewing this approach is to see it as a big picture perspective, allowing for more readily understandable explanations of mental functioning along a spectrum. The model may also help make sense of the comorbidity frequently observed between certain disorders (i.e., anxiety and depression). Determining accurate diagnoses of mass shooters is difficult, largely due to the often-retrospective nature of the task and the lack of reliable psychological or psychiatric data on them. However, the use of a dimensional model to categorize their mental functioning may be an acceptable alternative method when key data sources are limited. This approach may also help clear up misconceptions about the rate of psychosis in mass shooters, as well as which population of individuals carry more risk. For example, a testable hypothesis might be that most mass shooters fall into the externalizing domain, given their personality structure, defense mechanism use, absence of clear psychotic symptoms and inability to internalize and process their intrapsychic conflict in a prosocial manner.

Taking Dr Pies’ vignette of 19-year-old Tyler, we can apply the dimensional model to understand his likely position on the mental functioning spectrum, as well as analyze some of his proximal warning behaviors.4 Tyler’s strong beliefs about being targeted for mistreatment and resentment over life being stacked against him suggest he is likely heavily weighted towards externalization. When under stress, it is possible he might regress along the spectrum towards developing mild to moderate thought distortions and/or worsening paranoia. Turning to his proximal warning behaviors, we find evidence of conducting research and planning (pathway), an increasing pathological preoccupation with a cause (fixation), and admiration for previous shooters (identification). These three warning behaviors have been found in most school shooters and lone actor terrorists, and in particular, pathway and identification have discriminated between attackers and nonattackers.5 We also see he has a personal grievance toward his high school, as well as a recent loss of a job. He has expressed ideological beliefs that may further his intent to act (anger towards minorities, resentment towards his school). Given his rants on social media, it is possible he has developed a dependence on a virtual community which supports and encourages his beliefs. These are further indicators of risk, particularly among lone actor terrorists.6

Las Vegas shooter analysis

As a thought experiment, let us apply the same approach to better understand the Las Vegas (LV) shooter who opened fire into a crowd from the 32nd floor of the Mandalay Bay Resort and Casino on October 1, 2017.7,8 This case was notable for many reasons, not the least of which was the shooter’s purported absence of motivation and apparent “private nature.”7 The Las Vegas Review Panel (LVRP) found no evidence suggesting the LV shooter was motivated by ideological or political beliefs. However, the panel concluded that his “intention to die by suicide was compounded by his desire to attain a certain degree of infamy via a mass casualty attack.”7 It was also found that he had stressors of declining physical health, a substantial need for control, and a history of manipulating others. Of note, he had demonstrated an ability to maintain some interpersonal relationships and did not completely isolate himself. He displayed at least some amount of concern and responsibility for his girlfriend and certain family members. There was no evidence he had ever experienced psychotic symptoms. He was intelligent, methodical and had achieved significant financial success in the real-estate business. He also applied his intellect to a favorite pastime-gambling-and claimed to have won significant sums by applying algorithms he had discovered to gambling on machines. The FBI noted that he “displayed minimal empathy throughout his life and primarily viewed others through a transactional lens of costs and benefits”-an interesting finding given his biological father’s history of psychopathy and criminal infamy.7

However, in his final months he appeared to be misusing alcohol, seemed despondent and was experiencing financial stress. He had also obtained prescriptions for diazepam from his physician. He was an avid firearms enthusiast and collector, and there was at least one report that he was concerned about escalating government restriction of firearm ownership. The FBI found that he “engaged in significant, methodical, Internet-based research regarding site selection, police tactics and response, and ballistics.”7 He also applied his methodical intellect to conducting in-person site surveillance and meticulously planned and ensured he would be in control of his own suicide. It did not escape the FBI’s attention that he was likely influenced by the memory of his father who had “achieved” significant criminal notoriety and was diagnosed as a psychopath by a psychiatrist in 1963. What is not said in the FBI report is the possibility of heritability of psychopathy in the shooter, given his father’s absence as an actual parent, yet biological contribution to his son’s personality.

In applying the mental functioning spectrum to this case, we begin with his arguable “successful” psychopathy. His capacity for delaying gratification well enough to become financially successful in real estate, his lack of any significant criminal record, and his capacity for at least modest interpersonal relationships gives some pause. There is no evidence to place him in the psychotic domain, so we surmise that he would fit somewhere in the overlap between externalizing and internalizing. With mounting stressors and alcohol misuse, he would be likely to regress more squarely into the externalizing domain towards the end of his life. The externalizing domain would be associated with what Melanie Klein9 called the “persecutory position.” Per developmental theory, healthy development requires a transition away from Klein’s persecutory position to the “depressive position,” which would be more consistent with the internalizing domain.

Biopsychosocial impediments to psychological development can cause violent offenders to become relatively fixed in the persecutory stage, or what Klein has called the paranoid-schizoidposition.10 In this stage, much of an offender’s worldview is based on feelings of injustice and frustration over what is perceived as “intentional” harm, or purposeful withholding of gratification by the societal structure imposed by others. Fixation at this stage is associated with strong feelings of envy, resentment and the use of externalizing defense mechanisms such as projection, acting out and splitting. In contrast, the depressive position is associated with the capacity for regret, victim empathy and reconciliation with society. The depressive stage is associated with more internalizing, mature defense mechanisms such as sublimation, delaying gratification and anticipation.

The violent offender who functions in the externalizing domain often suffers from strong feelings of envy: what Klein referred to as the wish to destroy goodness. This offender may or may not be envious of other’s possessions or social status but will be very likely to be envious of the way in which others are able to enjoy their apparent status. Thus, the externalizing/envious offender’s goal is “to destroy the Other’s ability/capacity to enjoy” the prized object or status.11 There may come a point for such individuals when their resentful, nihilistic mindset leads them to feel that their “self” is already dead, and the death of their body is of little consequence. Such dynamics ultimately undermine the capacity for undistorted judgment, finding meaning in life, and sublimating aggression. They are now ready to override the survival instinct and fully embrace a drive towards death. 12 We call this the obliterative mindset, which seeks to destroy everything and embrace nothingness. A pointed example would be the mass murderer who attacked Congresswoman Gabriel Giffords in Tucson, AZ. He was increasingly drawn to nihilism as a philosophy and developed paranoid beliefs that the government was controlling the meaning of words. This case illustrates a violent offender who resides in the psychotic domain mental functioning.

Returning to the LV shooter, we suspect that he may have been an individual who initially functioned more in the internalizing domain. However, given his genetic predisposition for psychopathy and externalizing symptoms, he would have been at risk for regressing to the externalizing domain. As the FBI noted, the LV shooter had an “inability or unwillingness to perceive any alternatives” to carrying out his attack. We suspect that his regression to the externalizing domain and his nihilistic, obliterative mindset ensured his inability to inhibit his trajectory toward murder-suicide.

Recently, it has been reported that the LV shooter sent text messages to a girlfriend only two days prior to carrying out the attack.13 The alleged texts were sent to a 29-year-old woman with whom he had been having an affair, while at the same time having a long-term relationship with his girlfriend.  If the texts are genuine and credible, they appear to provide further support to our hypothesis that the LV shooter was functioning in the persecutory, obliterative mindset.  In the texts, he acknowledges having become a “recluse” because others in society could only be expected to hurt and disappoint him.  He states: “The best way to live life is with a wall between you and everyone else. So when they do hurt you, the sting isn’t so bad.” His persecutory mindset had become so entrenched and prominent by that point, that his use of externalizing defense mechanisms, such as externalization and projection, can be clearly seen.  For example, he states: “People these days are evil . . . It really doesn’t matter who they hurt in the process . . . People always eventually disappoint and hurt you.” The theme of projecting “evil” outside onto “society” is striking, and his comments may be seen as distorted references to himself: “People in society have become evil, self-loathing, selfish and entitled . . . They are more concerned with . . . the lives they see on the television [and] they don’t have a second thought about who they destroy on the way.”

Finally, from a psychological viewpoint, it is tempting to speculate he was motivated to some degree by a desire to achieve criminal infamy as his father had done, and perhaps Oedipally triumph over a father who attained notoriety for being on the FBI’s Ten Most Wanted. The shooter’s father held a “record” of sorts, having been on the FBI’s Ten Most Wanted list for about eight years (most wanted criminals were taken off the list in less than six months).14 The father remained a fugitive for many years, having escaped from a federal correctional institution. Like his son, he greatly enjoyed gambling and was last arrested in 1987 for racketeering related to his “bingo business” and fraud.15


The tripartite dimensional approach has stimulated a burst of recent research. Here, we draw on its overarching structure and combine it with evidence-based research on mass shooters to better understand the level of their mental health functioning, as well as their underlying psychodynamic structure. We have emphasized a dimensional approach to mental functioning, focusing on the usefulness of conceptualizing mental problems as psychotic, externalizing, or internalizing. This provides a means by which the mental health professional can discuss mass shooters who evidence psychological problems but fall short of a formal psychiatric diagnosis with other nonclinicians and members of the public.


Dr Knoll is Director of Forensic Psychiatry and Professor of Psychiatry at SUNY Upstate Medical University in Syracuse, NY. He is Editor in Chief Emeritus of Psychiatric Times (2010 to 2014).

Dr Meloy is Clinical Professor of Psychiatry at University California San Diego, La Jolla, CA.

The authors report no conflicts of interest concerning the subject matter of this article.


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7. U.S. Department of Justice: Key Findings of the Behavioral Analysis Unit’s Las Vegas Review Panel. Federal Bureau of Investigation. 2019. Accessed February 13, 2020.

8. LVMPD Preliminary Investigative Report Mass Casualty Shooting. Las Vegas Metropolitan Police Department. October 1, 2019. Accessed February 13, 2020.

9. Klein M. Envy and Gratitude, and Other Works. 1946-1963. New York: The Free Press; 1975.

10. Hyatt-Williams A. Cruelty, Violence and Murder: Understanding the Criminal Mind. New Jersey: Jason Aronson, Inc; 1998

11. Zizek S. Violence. New York: Picador; 2008.

12. Anderson MK. The death of a mind: A study of Shakespeare’s Richard III. J Anal Psychol. 2006;51:701-716.

13. Crick A, Boyle L. 'There are so many people who don't deserve to be alive.' Chilling texts Las Vegas shooter Stephen Paddock, 64, sent to his secret 29-year-old mistress before he opened fire and killed 58 revealed. Daily Mail. January 21, 2020. Accessed February 17, 2020.

14. Wallace A, Wallenchinsky D. Most Wanted by the FBI. Statesman Journal. Salem, Oregon. August 25, 1990. Accessed February 13, 2020.

15. Bernstein M. Las Vegas shooter's dad, on FBI's Most Wanted list, was arrested in Oregon in '78. The Oregonian. October 2, 2017. Accessed February 13, 2020.

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