In the aftermath of a mass shooting, the shockwaves often extend far beyond the immediate tragedy. According to a new study, these events can leave a troubling legacy: inspiring future attackers who mimic the original mass murderers, sometimes years or even decades later. These “copycat” shooters often share striking similarities with the perpetrators they emulate, including demographics and target locations. The study reveals that this phenomenon represents a persistent and insidious threat.

The Start of Something Terrible

“High-profile attackers can have exponential effects on inspiring generations of new attackers,” Adam Lankford, professor and chair of criminology and criminal justice at the University of Alabama, told PsyPost. “The notion that some people who commit mass shootings are not attacking for their own reasons — they’re copying a role model instead — is incredibly scary.”

The findings are stark. Nearly 80% of copycat attacks occurred more than a year after the original incident, with an average delay of eight years. This fact obviously challenges the assumption that copycat behavior is confined to the immediate aftermath of a high-profile event.

The 1999 Columbine High School massacre, perpetrated by Eric Harris and Dylan Klebold, has cast a long shadow over subsequent acts of mass violence. Their attack, which resulted in 13 deaths, has inspired numerous copycat crimes, a phenomenon often referred to as the “Columbine effect.”

In the years following Columbine, over 74 copycat cases have been reported, with 21 resulting in actual attacks. Many perpetrators cited Harris and Klebold as heroes or martyrs, explicitly referencing them in journals, videos, or online postings.

On March 15, 2019, Brenton Tarrant attacked two mosques in Christchurch, New Zealand, killing 51 people. Tarrant cited several earlier far-right attackers as inspirations, including Anders Behring Breivik, who carried out the 2011 Norway attacks, and Dylann Roof, responsible for the 2015 Charleston church shooting. Tarrant’s manifesto and actions have, in turn, inspired at least six other shootings.

To understand the dynamics of copycat shootings, Lankford and his co-author, Jason R. Silva, an assistant professor at William Paterson University, analyzed 205 cases of mass shootings influenced by earlier perpetrators. They compared these copycat attackers to their “role models” using demographic data, crime location types, and outcomes. Their findings reveal a disturbing pattern of replication.

Patterns of Sordid Imitation

The study uncovered that 98% of copycat shooters shared the same sex as their role models, and 68% shared the same race. Furthermore, 59% of copycats committed their crimes in the same country as their role models. Age alignment was particularly striking, with many attackers being the same age as their role models at the time of their crimes. “The age differences look remarkably like a bell curve or normal distribution,” Silva noted, describing a graph included in the study.

The similarities extended to the choice of targets. Copycats were nearly three times more likely to attack similar locations, such as schools or places of worship. The outcomes of these attacks — whether the perpetrators were arrested, died by suicide, or confronted law enforcement — were also frequently mirrored.

The delay between original attacks and copycat crimes shows just how enduring the influence of high-profile mass shooters is. This persistence can make it difficult to identify warning signs, especially when years pass before an inspired individual takes action. It adds a layer of unpredictability to an already horrifying prospect.

Lankford warned that even a past fascination with a mass shooter should not be dismissed. “Anyone who notices their family member, friend, or acquaintance has developed an unhealthy interest in a past mass shooter should consider that a serious warning sign, even if that perpetrator attacked many years ago,” he said.

Despite these troubling trends, the researchers found a notable difference: copycat shooters inflict less harm than their role models. On average, they kill ten fewer victims and injure 15 fewer people. Silva suggests this reduction may reflect “generation loss,” a phenomenon in which repeated acts diminish in intensity or impact over time.

Breaking the Cycle

The researchers argue that the media is an important factor in perpetuating copycat behavior. Extensive coverage of mass shooters, including their names, photos, and manifestos, can glorify their actions and attract new followers. Campaigns like “No Notoriety” advocate limiting such exposure, a recommendation strongly supported by the researchers.

“Copycat mass shooters appear almost entirely dependent on the media coverage of high-profile perpetrators, along with social media, for the information that drives their obsession and imitation,” Silva said. A such, it may be wise to rethink how these events are reported, balancing public interest with the responsibility to prevent further harm.

As society grapples with the growing threat of mass shootings, studies like this shed light on the invisible threads connecting these tragedies.

The findings appeared in the Journal of Criminal Justice.