The Buffalo suspect appears to have immersed himself on web forums like 4chan and 8chan, where versions of replacement theory abound. That is also where the suspect, before setting out to slaughter Black shoppers in Buffalo, posted a 180-page compendium of racist arguments and internet memes.

He wrote that he got his news from Reddit. He began browsing 4chan in May 2020 “after extreme boredom,” he wrote, and quickly found a gateway to anti-Black and antisemitic replacement content. Reflecting the most extreme versions of replacement theory, the suspect deemed Black people, like immigrants, as “replacers”: people who “invade our lands, live on our soil, live on government support and attack and replace our people.”

According to a detailed analysis by the Anti-Defamation League provided to The Times, the suspect’s screed plagiarized almost two-thirds of another manifesto — the one left by an Australian man who in 2019 murdered dozens of Muslims as they prayed in two mosques in Christchurch. In some instances, the Buffalo suspect replaced the Christchurch killer’s references to Angela Merkel, the former German chancellor, with George Soros, the billionaire philanthropist. One page of the Australian’s document includes a purported count of Jews working at the senior levels of major media outlets, including Fox itself.

Oren Segal, vice president of the ADL’s Center on Extremism, said that the Buffalo suspect’s repurposing of the Christchurch manifesto to justify an attack on Black Americans “demonstrates the evolving and interactive nature of extremist propaganda.”