Staring down the lens of a camera, a man with a high-pitched, heavily-accented voice introduced himself as “Anon” and began a hate-filled rant. “I think the Holocaust never happened,” he stated, before stammering into an incoherent tirade against feminism. “The root of all these problems is the Jew,” he concluded. “Would you like to be friends?”

It was the start of a 35-minute video that was live streamed on Twitch, an Amazon-owned video sharing platform that is most commonly used to broadcast video games like Call of Duty and Fortnite. By the end of the video, the man had killed two people in the eastern Germany city of Halle and attempted to enter a synagogue using homemade weapons, before being arrested.

Only five people were watching the Twitch stream at the time but thousands more saw the archived version before it was eventually taken down. Copies of the footage soon spread to other platforms, with an estimated 15,625 people viewing clips through public channels on the messaging app Telegram.

The method of live streaming the shooting through a head-mounted camera was reminiscent of the Christchurch terror attack in New Zealand earlier this year, during which a gunman indiscriminately opened fire on people inside two mosques, killing 51 people.

Whether it was intended to terrify minority communities or inspire copycat attacks, a German security official described it as “definitely the same modus operandi as Christchurch”.

Germany synagogue shooting: Halle attack in photos Show all 24 1 /24 Germany synagogue shooting: Halle attack in photos Germany synagogue shooting: Halle attack in photos Police officers secure a synagogue in Halle. At least two people have been killed in the shootings at multiple locations in Germany AP Germany synagogue shooting: Halle attack in photos A man shots from a long-barreled gun ATV Studio Halle/Reuters TV Germany synagogue shooting: Halle attack in photos A police tank patrols at a crime scene near the Synagogue. The attack came during Yom Kippur, a Jewish religious festival that sees observers fast and pray at synagogues to atone for sins. EPA Germany synagogue shooting: Halle attack in photos The shooter walking in Halle ATV Studio Halle/Reuters TV Germany synagogue shooting: Halle attack in photos One victim's body was in the street outside the synagogue, while another victim was said to have been shot at a nearby kebab shop dpa via AP Germany synagogue shooting: Halle attack in photos Policemen climb over a wall close to the site of a shooting in Halle dpa/AFP/Getty Germany synagogue shooting: Halle attack in photos The shooting took place in the eastern German city of Halle, with the incident taking place on Humboldtstrasse, which houses a synagogue and Jewish cemetery Germany synagogue shooting: Halle attack in photos Synagogue's in over parts of Germany had a police officer presence, including Dresden AP Germany synagogue shooting: Halle attack in photos Local reports said one of the victims was killed outside a kebab shop around 600m away, where witnesses told Focus the assailant was wearing a helmet mounted with a camera, and wearing combat fatigues dpa/AFP/Getty Germany synagogue shooting: Halle attack in photos Police officer runs on a road in Halle dpa via AP Germany synagogue shooting: Halle attack in photos Police guard a crime scene EPA Germany synagogue shooting: Halle attack in photos Bullet casings after the shooting Reuters Germany synagogue shooting: Halle attack in photos Police officers block a road AP Germany synagogue shooting: Halle attack in photos A spokesperson for the local Jewish community told Der Spiegel that up to 80 worshippers were inside the synagogue at the time, but security measures at the synagogue's entrance "withstood the attack" Reuters Germany synagogue shooting: Halle attack in photos Policemen walk through a street close to the site of a shooting dpa/AFP/Getty Germany synagogue shooting: Halle attack in photos Policemen climb over a wall close to the site of a shooting in Halle an der Saale, eastern Germany, on October 9, 2019. - At least two people were killed in a shooting on a street in the German city of Halle, police said, adding that the perpetrators were on the run. "Early indications show that two people were killed in Halle. Several shots were fired. The suspected perpetrators fled in a car," said police on Twitter, urging residents in the area to stay indoors. (Photo by Sebastian Willnow / dpa / AFP) / Germany OUT (Photo by SEBASTIAN WILLNOW/dpa/AFP via Getty Images) SEBASTIAN WILLNOW dpa/AFP/Getty Germany synagogue shooting: Halle attack in photos Police secures the area after a shooting in the eastern German city of Halle on October 9, 2019. REUTERS/Marvin Gaul. NO RESALES. NO ARCHIVES STRINGER Reuters Germany synagogue shooting: Halle attack in photos Police secure the area Reuters Germany synagogue shooting: Halle attack in photos A police officer walks onto the street at the scene of a fatal shooting in Halle Nonstopnews/Reuters TV Germany synagogue shooting: Halle attack in photos Germany synagogue shooting - Multiple people dead as gunman on run in Halle MZTV Germany synagogue shooting: Halle attack in photos Police block the area around the site of the shooting dpa/AFP/Getty Germany synagogue shooting: Halle attack in photos First responders attend to the scene Nonstopnews/Reuters TV Germany synagogue shooting: Halle attack in photos Police gather Reuters Germany synagogue shooting: Halle attack in photos Police secures the area after a shooting in the eastern German city of Halle on October 9, 2019. REUTERS/Marvin Gaul. NO RESALES. NO ARCHIVES STRINGER Reuters

But while the scale of the casualties was far smaller for the latest attack, so too was the reach of the video. In the 24 hours following the Christchurch attack, more than 300,000 versions of the stream were uploaded to Facebook alone.

In the months since, technology firms have been working hard to prevent the spread of distressing content and violent propaganda across social networks and video-sharing sites.

In a series of tweets following the attack, Twitch explained how it “worked with urgency” to remove the content and permanently suspend any accounts found to be sharing it. It took just 30 minutes for the original video to be flagged and taken down, and unlike the Christchurch video, the video did not continue to pop up on sites like YouTube and Twitter thanks to Twitch sharing the underlying code by which the footage can be immediately identified and removed.

“Once the video was removed, we shared the hash with an industry consortium to help prevent the proliferation of this content,” Twitch said. “We take this extremely seriously and are committed to working with industry peers, law enforcement, and any relevant parties to protect our community.”

What remains an issue is the spread of such content through messaging apps like Telegram and WhatsApp. Sharing the video through a private message means the data is encrypted and therefore cannot be identified by the apps in the same way.

It is only if the content is shared through public channels, such as those found on Telegram, that the content can be flagged and removed.

Megan Squire, a professor at the Centre for Analysis of the Radical Right, found that a manifesto file believed to come from the German attacker was also spreading on Telegram. Her analysis of the live stream's spread on Telegram found that it reached more than 10 public channels before being removed.

The Christchurch shooting was first broadcast to Facebook, before being uploaded and shared on sites like Twitter and YouTube.

At the time, online moderators described attempts to remove the footage as similar to a game of whack-a-mole. While this approach has become more effective through the sharing of video hash identifiers, it remains reactive.

Facebook is already working on the next step, which is to proactively recognise the videos as they are being live streamed. In order to do this, the technology giant has been training artificial intelligence algorithms to recognise videos of shootings as they are happening.

Footage captured on police body cameras during training exercises are being used to help train these algorithms, in the hope that future shootings will be instantly flagged or removed by this AI moderator.

"The technology Facebook is seeking to create could help identify firearms attacks in their early stages and potentially assist police across the world in their response to such incidents," said Neil Basu, the UK's top-ranking counter terrorism police officer.

"Technology that automatically stops live streaming of attacks once identified, would also significantly help prevent the glorification of such acts and the promotion of the toxic ideologies that drive them."

Facebook is working with law enforcement agencies in both the UK and US to develop these strategies, which could eventually find their way onto other platforms like YouTube and Twitch.