The suspect, who was in custody by noon, opened fire inside the Tree of Life Synagogue in the city's Squirrel Hill neighbourhood, according to The Associated Press.
There was a blue check mark next to Robert Bowers' name, meaning that the social media account was verified.
His bio said that "jews are the children of satan," his banner image a clear reference to a white supremacist meme. His last message, posted yesterday, read "Screw your optics, I'm going in."
The account is believed to belong to the same Robert Bowers who is suspected of opening fire in a Pittsburgh synagogue during prayers, killing 11 people and wounding six others.
The profile, which has since been removed, lived on Gab, a social media platform that has become a haven for white supremacists, neo-Nazis and other adherents to extreme ideologies that have found themselves increasingly unwelcome on Twitter and Facebook.
Founder Andrew Torba has long said Gab is simply a "free speech" platform for anyone who wants to join, and has responded aggressively to characterisations otherwise.
But the platform's history is tied to the white supremacists and other far-right figures who joined in its first months, and who have contributed to Gab's growth.
In the wake of the Pittsburgh shootings, Gab and Torba have girded themselves for war.
On his Gab account, Torba criticised mainstream media stories about his site and promised users that it would survive the increased attention.
After Gab was banned from PayPal and received notice from Joyent, its hosting provider, that it would pull their service, Torba wrote that "GAB IS NOT GOING ANYWHERE I don't care what we have to do, I don't care what it takes. We will build everything from the ground up if we have to. "
Torba's updates have kept Gab's users in the loop on the drama: Gab's Chief Technology Officer Ekrem Büyükkaya announced that he was stepping down because the "attacks from the American press have been relentless for two years now and have taken a toll on me personally". Torba said he'd secured a new host for his site.
Gab, through Torba, has always pitched itself as an alternative to Silicon Valley social media sites, attracting a user base of people who believe companies like Twitter and Facebook are deliberately censoring their views.
In 2016, when Twitter strengthened its policy against "hateful conduct" and banned a number of far-right and white supremacist accounts, Torba said Gab gained 60,000 users in eight days.
Personnel from Chesed Shel Emes Emergency Services and Recovery Unit gather near the Tree of Life Congregation in Pittsburgh. Photo / AP
The platform itself is a combination of many of the sites that Gab would like to replace.
The site works like a hybrid of Reddit and Twitter, where users can post character-limited messages, and respond, comment and vote other users' posts up or down.
Alex Jones, who has 55,000 followers on Gab, often promotes his live broadcasts there since he has been banned from YouTube and Twitter.
But Gab is more than a platform. It's also positioned itself as a key figure in the right-wing response to online crackdowns of extremist views, and has benefited directly from the white supremacists who flocked to Gab on the promise that their views would not be censored, according to an expert who has followed the site's growth.
Torba has become a charismatic leader of the "alt-tech" movement which, among other things, dedicates itself to protecting and building tech to house "free speech" - including extremist ideologies that are increasingly unwelcome on mainstream sites.
When James Damore was fired from Google in 2017 for writing a viral memo about women in tech, Torba capitalised on the case's media attention to promote an "alt-tech revolution," where conservative tech workers would rise up and topple Silicon Valley giants. Gab, of course, would be there to take their place.
Moments before the police say he barged into a Pittsburgh synagogue and opened fire, Robert Bowers posted one last message online on Gab, a social network that has become a haven for white nationalists, neo-Nazis and other extremists. https://t.co/fHpcC3yAQFpic.twitter.com/4kKPfl8sPk
Although the revolution did not come to pass as predicted, Torba managed to raise US$80,000 for a crowdfunding campaign to support his website in the days after Damore's story published, the Washington Post reported at the time.
He also gained the currency of media attention, giving interviews to several mainstream outlets promoting his site as a mainstream technology alternative.
Joan Donovan, the Media Manipulation/Platform Accountability Research Lead at Data and Society, noted that Gab has used crackdowns like the "hateful conduct" rule enforcement on Twitter to recruit for his own site.
Gab "rode the wave of attention to white nationalists after Charlottesville (Virginia) to populate its social media platform," Donovan said.
In the wake of the deadly Charlottesville protests in 2017, major companies like Apple, PayPal and Squarespace began removing white nationalists from their platforms, leaving them with fewer options for making money and hosting their views online.
Watching @juliaioffe and @oliverdarcy discuss with @brianstelter the hate that spreads on Gab and other platforms. The hate is not new, the “supercharged” amplification is. Julia: “when the ground is fertile all this stuff blossoms” pic.twitter.com/iRAZtLjB8T
Gab was there to pick up the slack. "Over the past year, Gab has been able to grow and add new features, premium features, streaming features," Donovan said, "because of the fusion of the white supremacist need for platforms" and the website's promise of a free speech haven.
In the Pittsburgh shooting's aftermath, Christopher Cantwell - one of Gab's most prominent anti-Semites who achieved notoriety during last year's Charlottesville rally - began trafficking in anti-Jewish slurs and conspiracy theories that the gunman was a plant from American spies to foment anger against conservatives before the Midterms.
Cantwell, known as the "Crying Nazi," made a name for himself during the Charlottesville rally when he pepper-sprayed counterprotesters and was featured in a viral Vice documentary. On Gab, he frequently bashes Jews and African-Americans and encourages followers to followers to listen to his podcast, Radical Agenda.
He also attacks the news media, though he seems to have an affinity for Fox News. "The one good thing about this ... shooting is that I know I'm not missing anything by turning off Fox News," he wrote this weekend, using an offensive slur for Jewish people. "This is all they'll be talking about from now until election day."
But he also let his followers know that he was worried Gab might be shutting down soon and shared links where people could still follow and interact with him. "I know Gab is the only way some of you keep up with me, and it looks like that might be a problem," he wrote.
Stating the obvious. But anyone who has been on or looked at Gab will tell you the platform is not a free speech forum. It’s a forum for right wing hate speech which occasionally gets banned on Twitter. https://t.co/5RY9gaVToK
Although Gab's relationship to the white supremacists who congregate there can be contentious at times, Torba is extremely good at turning criticism of the platform - and the extreme views it houses - into calls to action and attention.
Months ago, Torba started declining all mainstream media requests for interviews, a fact that Gab promotes on their social media accounts. In response to questions about Bowers's account, the Post was sent a statement on Medium that said Gab had removed it and was cooperating with law enforcement. The site didn't immediately respond to a request for an interview.
Torba appears to be hoping for the ultimate attention intervention as Gab faces scrutiny. Torba posted a plea on Gab for a word of support from the president:
"I don't brag about this, but in 2016 across all of my accounts I had BILLIONS of impressions supporting and defending him and America. Can we get one tweet defending Gab.com, our work with law enforcement to bring a terrorist to justice, and our defense of free speech online for all people?
"Is that too much to ask?"
Gab founder/CEO Andrew Torba declared last night that "GAB IS NOT GOING ANYWHERE."
"We will build everything from the ground up if we have to. We may be down for a few weeks....We will figure it out." pic.twitter.com/I9HAtNsC0i
