Integrating the Literature on Lethal Violence: A Comparison of Mass Murder, Homicide, and Homicide-Suicide

• Author: Emma E. Fridel
• DOI: 10.1177/10887679211002889
• Published date: 01 May 2022
• Date: 01 May 2022
• Subject Matter: Articles

https://doi.org/10.1177/10887679211002889

Homicide Studies

2022, Vol. 26(2) 123 –147

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DOI: 10.1177/10887679211002889

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Article

Integrating the Literature

on Lethal Violence: A

Comparison of Mass Murder,

Homicide, and Homicide-

Suicide

Emma E. Fridel1

Abstract

Although mass murder is traditionally examined as a separate construct from homicide

generally, few studies have explored their similarities and differences. This study

compares the incident, victim, and offender characteristics of: (1) mass murderers

and homicide offenders; and (2) mass murder-suicide offenders and homicide-suicide

perpetrators. Mass murderers are more likely to be male; commit suicide; kill young,

white, and female victims; use firearms; co-offend; operate in public places; and kill

as part of drug trafficking and/or gang warfare. The analysis demonstrates that mass

murderers are distinct from both homicide and homicide-suicide perpetrators, and

represent a unique type of violent offender.

Keywords

mass murder, homicide-suicide, mental illness, data merging

Introduction

With 43 attacks claiming over 200 victims, mass killings reached a forty-year high in

2019 (AP/USA TODAY/Northeastern University, 2019). Defined as the killing of

four or more individuals (excluding the offender) within 24 hours, mass murders are

incredibly rare events that account for less than 1% of all homicides (Krouse &

Richardson, 2015). Despite their rarity, mass killings disproportionately impact pol-

icy due to widespread public concern. According to the American Psychological

1College of Criminology and Criminal Justice, Florida State University, FL, United States.

Corresponding Author:

Emma E. Fridel, College of Criminology and Criminal Justice, Florida State University, 408 Eppes Hall

Tallahassee, FL 32306, United States.

Email: efridel@fsu.edu

1002889HSXXXX10.1177/10887679211002889Homicide StudiesFridel

research-article2021

124 Homicide Studies 26(2)

Association (APA, 2019), nearly 80% of American adults experience stress related to

mass shootings, and approximately one third avoid certain places and events due to

their fear of victimization. Individual incidents have fueled moral panics, inspired

social movements like March for Our Lives, and sparked calls for policy change on

topics ranging from gun control to mental healthcare reform.

Despite this surge of public interest, little research has explored the correlates of

mass murder. The extant literature has largely focused on estimating the prevalence

of the crime (Duwe, 2004; Liem et al., 2013), identifying risk factors and developing

a basic offender profile (Fox & Levin, 1998; Knoll, 2010a, 2010b; Knoll & Meloy,

2014; McPhedran, 2017), and classifying incidents into unique subcategories (Bowers

et al., 2010; Petee et al., 1997). With a few notable exceptions (Fridel, 2021; Lankford,

2015, 2016), this work has almost exclusively been descriptive in nature and relies

heavily on case studies. While these types of analyses provide rich detail on specific

incidents, they overemphasize the most atypical and extreme cases, are not represen-

tative of or generalizable to the population as a whole, and may propagate stereo-

types. The dearth of empirical research on mass murder is a natural consequence of

its low base rate and corresponding lack of reliable and/or official data (Huff-Corzine

et al., 2014).

Compounding these data issues is the long-term conceptualization of mass murder

as a psychological—rather than sociological or criminological—problem. Dismissed

by most criminologists as aberrant events unlikely to be explained by social processes,

mass killings have traditionally been considered the domain of psychiatrists and psy-

chologists (Dietz, 1986; Knoll, 2010a, 2010b; Marzuk et al., 1992; Meloy et al., 2004;

Pies, 2020). Indeed, much of the early work in this area focused on diagnosing surviv-

ing offenders as “berserk” or “violent paranoid,” determining narcissistic injury, nihil-

ism, and the superman complex to be important developments in the psychopathology

of these offenders (Knoll & Meloy 2014; Palermo, 1997).

Additionally, mass murder has largely been considered as a unique form of homi-

cide, one so distinct as to merit an independent body of literature. This artificial divide

between the study of mass killing and homicide is problematic for several reasons. The

most widely accepted definition of mass murder, for example, was established in the

1980s with little to no justification as to why offenders with four or more victims in a

single incident should be considered qualitatively distinct from other homicide perpe-

trators (Ressler et al., 1988). Few studies have validated the fundamental assumption

that mass murder is a unique construct by moving beyond descriptive comparisons and

quantitatively examining its relationship with criminal homicide. It is impossible to

contextualize risk factors for mass murder properly without directly comparing these

killers to other homicide perpetrators; most studies developing offender profiles, for

example, make claims that mass killers are more or less likely to exhibit certain traits

without explicitly defining the reference group (presumably other homicide offend-

ers). More importantly, the segregation of mass murder research prevents scholars

from drawing upon the theoretical and methodological advances of the broader homi-

cide literature.