The 18-year-old who allegedly killed 10 people and wounded three others when he opened fire at a grocery store in a majority-Black neighborhood in Buffalo, New York, appears to have left behind an archive of writings and posts that reveal an extremely online — and extremely familiar — ideology of hate that was heavily influenced by memes and copy-and-paste propaganda.

In the weeks and days before the shooting, a person identifying themselves as the alleged shooter, Payton Gendron, uploaded a 180-page self-described “manifesto” and more than 600 pages of archived posts from the messaging app Discord to different online storage websites.

In these documents, Gendron laid out his racist and antisemitic ideology, explained his motivations for mass murder, and quite literally mapped out the means by which he intended to carry it out and, as the Washington Post reported Monday, the surveillance measures he took to make sure it was successful.

He also explicitly states that it was 4chan, a controversial online message board, where he was “awakened” to the conspiracy theory that was the driving force behind his actions: the “Great Replacement Theory.”

“The ‘Great Replacement’ is a white supremacist antisemitic theory that claims that shadowy globalist forces are conspiring to replace white, largely white European, people with the ‘other’: persons of color and minorities,” Jon Lewis, a research fellow at the George Washington University Program on Extremism, told BuzzFeed News.

Much has been written about Gendron’s self-proclaimed beliefs in the context of the wider American political and media ecosystem. Fox News host Tucker Carlson has particularly come under fire for his past statements promoting replacement theory on his popular show.

But the documents Gendron left behind spell out his beliefs, and they are not the actions of a political partisan or a right-wing media devotee. In his writings he attacks the media industry, claiming it is controlled by Jews, aka “the enemy.” He identifies himself as an “eco-fascist national socialist,” explicitly says that he is not a conservative, and attacks both major American political parties.

Above all else, Gendron is a creature of the internet, born of memes and message board posts. Scattered throughout the hundreds of pages of documents he uploaded for posterity are screenshots and infographics from message board threads and copied-and-pasted screeds (“copypasta”) from extremist websites.

In a Discord message posted five months ago, on Dec. 20, he even refers to his planned mass murder as an extension of his online activity: “It’s time to stop shitposting and time to make a real life effort shitpost. I will carry out an attack on the replacers.”

The most defining feature of Gendron’s self-described “manifesto” is how unoriginal it is. When BuzzFeed News ran Gendron’s document through online plagiarism checker software provided by Grammarly, it gave it a score of 63% and showed that whole paragraphs had been copied and pasted from 4chan threads and racist and antisemitic websites with names like “The Truth About n-words” and “Jewery Exposed.” The document also borrows a large amount of text from the writings of another mass shooter: Brenton Tarrant, who killed more than 50 people in targeted attacks on mosques in Christchurch, New Zealand, in March 2019.

In his own document, Gendron writes that he was “radicalized the most” by Tarrant, and says that viewing a livestream of the mosque attacks “started everything you see here.” He refers to the Christchurch killer as “Saint Tarrant” in a Discord message posted Jan. 3, and in a series of posts on March 30 discussing his “manifesto,” he wrote, “I stole lots of info from Tarrant because I can’t say it any better.”

Nowhere in the hundreds of pages of documents Gendron left behind does he associate himself with a political party. In fact, he attacks the American two-party system.

In his document’s question-and-answer section, Gendron answers in the negative when “asked” if he is a conservative. “No, conservatism is corporatism in disguise, I want no part of it,” he said. In a few responses above, he states that it would be accurate to call him a “fascist” because “fascism is one of the only political ideologies that will unite Whites against the replacers.” He later writes that “conservatism is dead.”

Gendron explicitly states that he got his “current beliefs” from the internet, and the only mention of Fox News in all of his uploads is an infographic showing Fox as one of the enemy-controlled media outlets.