The New York State Attorney General is investigating the role that social media sites like 4chan and Discord may have played in the May 14 shooting at a Buffalo grocery store that left 10 people dead and three more injured.
Attorney General Letitia James said Wednesday that her office would be looking at the online resources the accused gunman, Payton Gendron, "used to discuss and amplify his intentions and acts to carry out this attack."
"The fact that an individual can post detailed plans to commit such an act of hate without consequence, and then stream it for the world to see is bone-chilling and unfathomable," James said in a statement specifically naming Discord, 4chan, 8chan and Twitch.
Amazon, which owns Twitch, and Discord didn't immediately reply to requests for comment.
Police report that Gendron promoted racist propaganda extensively online before the shooting and discussed plans to terrorize an elementary school, church or other location he believed would have a considerable number of Black people present.
James told NPR on Tuesday that the shooting at Tops Friendly Markets on Jefferson Avenue was a case of domestic terrorism fueled by "a racist theory which has been propagated by those on social media as well as on cable news and by some elected officials."
Gendron livestreamed the attack on Twitch and posted a 180-page screed online that detailed the so-called great replacement theory, which falsely claims white Christians are being "replaced" in the US by people of color, Jews, Muslims and other minorities.
In an earlier statement, a Twitch spokeswoman said the site "has a zero-tolerance policy against violence of any kind and works swiftly to respond to all incidents."
Some civil rights advocates have called on social media platforms like Twitter and Facebook to ban posts that propagate the great replacement theory, much as they do Holocaust denialism.