Law enforcement sources believe the shooter posted a 180-page “manifesto” on 4chan, which embraces racist and anti-Semitic tropes and fixates on “replacement theory,” a white supremacist conspiracy theory that nonwhite people are replacing white people through immigration. In the document, the shooter included photos of himself, described why he would carry out the attack, and praised the New Zealand mosque shooter and South Carolina church shooter too. 

In a statement, the Justice Department said it is investigating the incident as a hate crime and an act of racially-motivated violent extremism. 

Domestic violent extremism is a growing problem in the United States, and will likely worsen over the next several years. Since 2015, right-wing extremists have been involved in 267 plots or attacks and 91 fatalities, far-left extremists in 66 incidents and 19 fatalities, the most in 25 years, according to data compiled by the Center for Strategic and International Studies. 

In fact, a report published by the Office of the Director of National Intelligence in 2021 assessed that racially or ethnically motivated violent extremists present the “most lethal” threat.

The report also assesses that domestic violent extremists exploit several popular social media platforms, smaller websites with a targeted audience, and encrypted chat applications to recruit new adherents, plan and rally support for violence and disseminate materials that contribute to radicalization and mobilization of violence. In this case, the attacker allegedly live-streamed the attack on Twitch, an American video live streaming service. The video, however, was removed less than two minutes after the attack started.

“The user has been indefinitely suspended from our service, and we are taking all appropriate action, including monitoring for any accounts rebroadcasting this content,” the company said. The Federal Bureau of Investigation (FBI) is asking anyone who has photos or videos related to the mass shooting to submit them to a newly created website. 

FBI Director Christopher Wray told Congress in 2021 that “white supremacists comprise the biggest chunk of our domestic terrorism portfolio overall” and “have been responsible for the most lethal attacks over the last decade.” 

For more articles on the threat of domestic violent extremism and risk strategies, visit: 

• The Rise of Extremism
• Risk mitigation for domestic terrorism and radicalization
• Planning for domestic violent extremism in large venues
• Family affiliated extremism and the siege at the U.S. Capitol
• Extremism in the United States in 2021: What’s out there and where are the risks?
• The Incel Killer and the Threat to the Campus Community
• The attack cycle, mass shootings and lone wolves: What companies should know