Before going on a shooting spree at the Chabad of Poway synagogue in Southern California, the alleged perpetrator posted a letter on the website 8chan. It echoes last month's New Zealand shootings, in which the alleged perpetrator took to 8chan to announce the attacks on mosques in Christchurch.
8chan is the latest website to come under scrutiny in the debate over the Internet's role in radicalizing extremists.
The site, where like-minded users with various interests interact with each other, particularly appeals to people who feel pushed off mainstream social media platforms like Facebook and Twitter. It includes communities that discuss Japanese cartoons and Game of Thrones.
But journalist Robert Evans, who writes for Bellingcat, an online investigative platform, describes some corners of 8chan as "a neo-Nazi gathering place on the Internet where young men try to convince each other to commit acts of terrorism."