Before allegedly murdering 11 people at a Pittsburgh synagogue, Robert Bowers claimed he was working to expose a left-wing blogger’s home address.

Bowers spent months writing violent right wing and anti-Semitic posts on Gab, an extremist-friendly social media network. (Hours before his alleged massacre at the Tree of Life synagogue, he posted on Gab “screw your optics, I'm going in,” shortly before the massacre.) In July, he told the spokesperson for a hate group that “i can get you the most recent” address for a blogger who was critical of the far right.

Although Bowers was a relatively unknown user on Gab, he frequently interacted with some of the site’s most prolific anti-Semites, according to research by the Southern Poverty Law Center.

One of those users was Brad Griffin, a spokesperson for the neo-Confederate hate group League of the South, who was present at 2017’s deadly white supremacist rally in Charlottesville, Virginia.

In July, Griffin (who uses the pseudonym “Hunter Wallace”) posted that he knew the identity of an anonymous blogger who was monitored far-right extremism. Griffin claimed to have the blogger’s “most recent address and tons of things about him that I haven’t posted.” Bowers responded that the address Griffin had “is not the most current for him. i can get you the most recent outside of gab.”

The July post was first flagged by Michael Hayden, an extremism researcher for the social media intelligence agency Storyful.

“Brad Griffin often expressed a desire on Gab to out a left-wing blogger who tracked the far-right,” Hayden told The Daily Beast.

By July 2018, Griffin posted what appeared to be the blogger’s name “and the names of his family members, and he took that information to Gab where he knew men like Bowers would take an interest in it,” Hayden said.

“I remembered seeing Bowers jump into the conversation, offering help track this man down,” Hayden said, adding that the blogger’s “only apparent offense was to report on the organizational habits and legal troubles of white nationalists.

“But to Bowers and Griffin, he was an enemy of the white race, and they wanted him gone. The truth is undeniable: the blogger's life was in real danger that day and Gab helped make that situation possible by pairing men like Griffin and Bowers together to organize.”

Bowers’ offer to contact Griffin “outside of Gab” implies that the neo-Confederate and the future alleged mass murderer were in contact on other platforms.

The blogger, whose name The Daily Beast is not disclosing, said he was rattled by the revelation that Bowers had targeted him.

“I was incredibly shaken at the discovery that an alleged mass murderer was apparently sharing my information online,” he told The Daily Beast. “It’s very disturbing. What’s more disturbing is that the people he was sharing my info with are still operating day to day with no consequences for their actions”

“Doxxing” or publishing a person’s personal information -- including their home address -- is against Gab’s terms of service. Although Bowers appears to have facilitated the dox on Gab, it’s unclear whether he posted the address on the site. Gab also has private messaging, which is not publicly searchable. The website has stated that it is cooperating with law enforcement on Bowers’ case.

“ As an Arab-American and a reporter, I had people threaten my life on that website too many times to even count, and Torba frequently ignored my requests for help with the problem. ” — extremism researcher Michael Hayden

But other Gab users have flaunted the site’s anti-doxxing policy, as well as a rule that prohibits “calling for the acts of violence against others, promoting or engaging in self-harm, and/or acts of cruelty, threatening language or behaviour that clearly, directly and incontrovertibly infringes on the safety of another user or individual(s).”

Gab bills itself as a “free speech” platform, but the hate is a vital part of its business model.

Gab CEO Andrew Torba “sought to profit off of the hate and vitriol that erupted in America during the 2016 election by providing a home for social media users who were banned for harassing and abusing people on mainstream platforms,” Hayden said. “The marketing campaign talked about free speech, but it was white nationalists and serial harassers like Andrew Anglin of Daily Stormer who made the site viable in its early going.”

A February 2018 study by researchers at Princeton University, University College London, and Cyprus University of Technology also highlighted Gab’s popularity among white nationalists.

“We observe that we have peaks for account creation on November 2016 and August 2017. These findings highlight the fact that Gab became popular during notable world and politics events like the 2016 US elections as well as the Charlottesville Unite the Right rally,” the study found. It also noted that “by looking at the posts for hate words, we also found that 5.4% of the posts include hate words. Finally, using changepoint analysis, we highlighted how Gab reacts very strongly to real-world events focused around white nationalism and support of Donald Trump.”

Threats on Gab, particularly against opponents of the far-right were a daily occurrence, Hayden said.

“As an Arab-American and a reporter, I had people threaten my life on that website too many times to even count, and Torba frequently ignored my requests for help with the problem,” he said. “Gab is a small community with only a handful of active users in comparison to Twitter or Facebook, so you would have to be blind or complicit in this behavior to pretend it did not happen.”

On Thursday, researcher Megan Squire tweeted Gab screenshots of Griffin boasting about doxxing her earlier this year.

She included screenshots of Gab users explicitly calling for her death. “Somebody needs to explain to me why this isn’t a violent act that should be repaid in kind,” the person wrote about a Wired article that described her work monitoring and reporting violence on the far-right.

The person had addressed the comment to Torba, who had apparently posted about the article.

Torba frequently authors vitriolic Gab and Twitter posts about individual critics, sometimes making unsubstantiated claims about them. As the proprietor of a website frequented by violent extremists, the tactic seems ill-advised, particularly after Gab was used to announce a mass murder on Saturday.

On Friday, Gab was back to complaining that users who violated site rules were actually “bogus accounts” by activists. Bowers, the Gab user and alleged mass murderer who posted violent anti-Semitic content, is currently awaiting trial on at least 29 felony counts.