On Thursday morning, less than 24 hours since the attack on a synagogue in Halle, Germany, a young man sits in front of a computer screen, taking part in a live chat. He is a gamer and hosts his own channel on Twitch, the streaming platform used by synagogue attacker Stephan B.* to livestream his killing spree on the internet the day before.

Usually, the gamer uses Twitch to meet like-minded people and play games.. This time, however, he wants to talk. "I'd never have thought that something like this could ever happen here, that somebody can crack up like this. I thought we shouldn't have a game today but have a chat instead," the man types into the computer. Being from Halle, he was close to the events when they unfolded. He expresses disbelief and horror: "He was like me, after all. He was livestreaming on Twitch, he had an official profile here."

The man has more than 20,000 followers on his platform. It only takes a few minutes before he receives a couple of comments. One user flatly asks, "Where can I find the original video?" He has the complete footage of the Christchurch attack saved on his mobile as well, he says.

'Coordinated circulation' of attack video

Stephan B., the suspect who confessed to the attack on the synagogue in the eastern German city of Halle, had created his Twitch profile only two months ago, the streaming platform said in a Twitter statement . Obviously the suspect had created the profile with the purpose of spreading live coverage of his act. Prior to the attack, the assassin had only used it once previously.

Twitch, a subsidiary of Amazon, removed the video after 30 minutes. But according to the platform, by the time it was removed it had already been viewed by some 2,200 people. Five were watching it live. After the deletion of the video, it was disseminated by users via messenger services in a coordinated manner, Twitch added.

Megan Squire, a US-based computer scientist, tries to shed light into the dark corners of the internet. Squire has kept track of the video's circulation via messenger services. On one of them alone (Telegram), it had already found an audience of some 55,000 people by Thursday evening, one day after the attack, according to Squire.

Virtual backing

The attacker had posted a crude PDF document on the internet in which he announced that he intended to diffuse the footage of his act in order to strengthen "the morale of other suppressed whites." The document is written in English; when he livestreamed his attack, some of Stephan B.'s voiceover comments were in English as well.

Via the internet, the Halle assassin clearly addressed an international right-wing audience, concludes Matthias Quent, an expert on right-wing extremism. "What he had in mind was to get through to the international haters, anti-Semites and racists who prowl the internet gaming scene's various sub-channels and other social networks," says Quent, a sociologist at the Jena-based Institute for Democracy and Civil Society. "He wanted to impress them and incite them to commit such acts themselves, and kill Jews in particular."

Read more: How empathy can actually fuel radicalization online

Even if the synagogue attacker allegedly acted alone in Halle, Quent affirms that "they're not isolated. They're part of an ideological movement, also part of social exchange processes, only to a lesser extent on the ground, but in a virtual area."

Berlin-based political analyst Jens Rathje has been studying right-wing extremism for years as well. Radicalization of mostly young men takes place predominantly on image boards, explains Rathje, who is working for the Amadeu Antonio Foundation. Initially, those image boards were created for the purpose of sharing Asian comic strips. Then politics gradually came into the picture.

Image boards such as 4chan and 8chan allow users to act in complete anonymity and practically without any form of moderation. "Those people grew up within this community. They associate themselves with it and identify themselves with this extremely right-wing ideology," says Rathje, adding that "this is where they find support and encouragement, and if they commit terrorist attacks, they might even receive a rating."

Read more: Germany records uptick in far-right extremist violence

German special police escort suspect Stephan B. as he arrives prior to a hearing in federal court

Ridiculing victims

In the wake of the Halle attack, some exchanges between users were downright inhuman, as one of the chats on the 4chan image board shows. Next to posted photographs of the woman who was shot by the attacker, some users call for ridiculing the victim and spitting on her grave.

A number of times, the chat links to the 35-minute original version of the video livestreamed by Stephan B., which has evidently been viewed by almost everybody here.

The second victim of the Halle assassin, the man who was shot in the kebab shop, is also ridiculed by one of the chat participants. In drastic terms, he delights in the victim's fear of death, which is clearly recognizable in the video. In addition, he calls the perpetrator an amateur because Stephan B. failed to kill more people with his homemade weapons.

Read more: Twitter policy targets 'dehumanizing' posts about religious groups

Watch video 02:46 Share Far-right 'enemy lists' Send Facebook google+ Whatsapp Tumblr linkedin stumble Digg reddit Newsvine Permalink https://p.dw.com/p/3NveD Germany's far-right 'enemy lists'

Platforms reward polarization

Image boards such as 8chan and 4chan are relatively small platforms that attract only a very small proportion of society. Berlin-based internet activist Markus Beckedahl has found out that users who are active on image boards mostly use other, larger platforms such as Facebook, Instagram or Twitter as well.

On those larger platforms, algorithms reward engagement and interaction, so that postings and comments that polarize or promote fear and ultimately hatred receive a higher ranking. As a result, they are more likely to be recommended to users than balanced or neutral postings. "According to some research, YouTube, for example, favors spreading radical and polarizing content," says Beckedahl. "Those who have visited YouTube were probably surprised to find that, via the 'related videos' function, they were redirected rather quickly to obscure conspiracy theory channels."

Meanwhile, Facebook is increasingly cracking down on hate speech following criticism and fines in Germany. The massive platform is now deleting postings and blocking users. Facebook users react by flocking to other platforms, to the so-called dark social area, where internet traffic is hardly accessible from the outside. This includes closed groups in messenger services such as WhatsApp or Telegram, where both the video and the inflammatory pamphlet originated by the Halle attacker continue to circulate.

According to political analyst Jens Rathje, right-wing extremists have identified the internet as exactly what it is: a platform with very few boundaries when it comes to international networking and communication.

Nadine Wojcik and Julia Bayer contributed to this report.

*Editor's note: Deutsche Welle follows the German press code, which stresses the importance of protecting the privacy of suspected criminals or victims and obliges us to refrain from revealing full names in such cases.

Every evening, DW's editors send out a selection of the day's hard news and quality feature journalism. You can sign up to receive it directly here.