A consortium of researchers dedicated to improving the understanding of the human causes and consequences of terrorism

Discussion Point: Is Aaron Alexis part of a larger phenomenon of lone-actor grievance-based violence?

The following is part of a series of thought pieces authored by members of the START Consortium. These editorial columns reflect the opinions of the author(s), and not necessarily the opinions of the START Consortium. This series is penned by scholars who have grappled with complicated and often politicized topics, and our hope is that they will foster thoughtful reflection and discussion by professionals and students alike.

Is Aaron Alexis part of a larger phenomenon of lone-actor grievance-based violence?

Aaron Alexis is the most recent example of a workplace mass killer, but some years ago the U.S. Post Office had enough of these examples that the phenomenon came to be referred to as “going postal.” Almost all of these cases involve a lone actor: an individual who plans and carries out an attack without help from any larger group or organization. We do not yet know the grievance that motivated Alexis’s rampage at the Washington Navy Yard on the 16th of September, but there may be some help in understanding Alexis if we ask how he might be similar to lone-actor assassins, lone-actor school attackers, and lone-wolf terrorists.

In a 2013 study published in Perspectives on Terrorism, Sophia Moskalenko and Ben Van Son joined me in trying to learn about lone-wolf terrorists by looking for the common characteristics of two categories of mostly lone-actor violent offenders: assassins and school attackers. The study used existing U.S. government-sponsored reports to examine these two kinds of offenders.

The logic of comparing school attackers with assassins is that these two groups of offenders are like lone-actor terrorists in perpetrating planful violence fueled by grievance. To the extent that assassins and school attackers share common characteristics, these characteristics may be risk factors for lone-actor terrorism as well.

The obvious demographic differences between the two groups (teenage school attackers vs. adult assassins) are actually a strength of the comparison: any commonalities uncovered are the more striking and unlikely to be a reflection of life status or demographic factors.

Our study found four common characteristics of assassins and school attackers: personal or group grievance; history of mental health problems, especially depression; unfreezing (weak or broken social ties); and weapons use outside the military. These four characteristics suggest the importance of means and opportunity for perpetrating violence. Grievance is a motive for violence, weapons experience provides a means, and the pain of mental health problems and social disconnection lower the opportunity cost of violence as the perpetrator has less to lose.

We offered two possible interpretations of these results. One possibility is that lone-wolf terrorists are importantly different from lone-actor assassins and school attackers. This possibility depends on finding characteristics of lone-wolf terrorists that are not shared with lone-actor assassins and school shooters. The second possibility is that lone-wolf terrorism is just one part of a larger phenomenon of lone-actor grievance-based violence. In this view, lone-wolf terrorists differ from lone-actor assassins and school attackers only in the accident that their grievance is one that observers would call political.

The second possibility, that there is a possible profile of individuals perpetrating lone-actor grievance-based violence, may be extended to include workplace shooters. We did not study workplace shooters, but the common characteristics of school attackers and assassins may appear in the case of Aaron Alexis.

As already noted, we do not yet know the grievance behind Alexis’s rampage. But news reports indicate that he had a history of mental health problems, including paranoia and hallucinations that might indicate schizophrenia. Most clearly, he had weapons experience outside the military: he was practicing at a shooting range shortly before his attack. More than that, he was involved in at least two shooting incidents. In 2004 he shot out the tires of a construction worker who mocked him. In 2010 he was arrested for shooting into the ceiling of his apartment, apparently in reaction to noise from his upstairs neighbor.

His personal history is still cloudy, but it appears he was a loner to the extent that he had few friends and his computer-services job with Experts sent him to temporary work in many different places, including Rhode Island, Massachusetts, Virginia, and the Washington Naval Yard. His mother lives in Brooklyn, but his last stable situation seems to have been in a suburb of Ft. Worth, Texas, where he was living with a Thai friend and working in his friend’s Thai restaurant. This relationship soured after his friend married and no longer had time for Alexis. According to a police report, Alexis tried to damage his friend’s car. In July 2013 Alexis moved out, a sudden disconnection from friend, job, and home.

As more information becomes available, the four characteristics of lone-actor grievance-based violence may emerge more clearly. Of course the great majority of individuals with a grievance do not turn to violence. The great majority of disconnected loners do not turn to violence.

The great majority of individuals with mental health problems, even paranoia problems, do not turn to violence. And the great majority of individuals with weapons experience outside the military do not turn to violence (although Alexis had already a history of illegal firearms use). The usefulness of the four characteristics will be determined by research in which we find out how many individuals have all four characteristics but never turn to violence. It is possible that having all four characteristics will be closely enough connected with lone-actor violence that special help might be extended to these individuals.



McCauley, C., Moskalenko, S., & Van Son, B. (2013). Characteristics of lone-wolf violent offenders: A comparison of assassins and school attackers. Perspectives on Terrorism, 7(1), 4-24.*

*This research was supported by the United States Department of Homeland Security Science and Technology Directorate Office of University Programs through the National Consortium for the Study of Terrorism and Responses to Terrorism (START), grant number N00140510629. However, any opinions, findings, and conclusions or recommendations in this document are those of the authors and do not necessarily reflect views of the U.S. Department of Homeland Security.

Clark McCauley (B.S. Biology, Providence College, 1965; Ph.D. Social Psychology, University of Pennsylvania, 1970) is Rachel C. Hale Professor of Sciences and Mathematics and co-director of the Solomon Asch Center for Study of Ethnopolitical Conflict at Bryn Mawr College. He is researcher in the National Consortium for the Study of Terrorism and Responses to Terrorism and a member of its executive committee. His research interests include the psychology of group identification, group dynamics and intergroup conflict, and the psychological foundations of ethnic conflict and genocide. He is founding editor of the journal Dynamics of Asymmetric Conflict: Pathways toward Terrorism and Genocide. You can contact him at cmccaule@brynmawr.edu.


Research Area