New York (CNN Business) Right before a suspected gunman walked into the Tree of Life synagogue in Pittsburgh on Saturday, he logged onto Gab and wrote to his followers, "I can't sit by and watch my people get slaughtered. Screw your optics, I'm going in."

Gab has now removed the suspect's profile. But his digital footprint leaves little doubt that anti-Semitism fueled his act of terror.

The suspect, Robert Bowers , frequently targeted Jews in his posts. He complained that President Donald Trump was surrounded by too many Jewish people. He used anti-Semitic slurs and wrote about an "infestation." He posted pictures of his handgun collection.

So why was he using Gab? Well, the website bills itself as "the free speech social network."

Gab is relatively small. But it has an avid user base. It was founded by entrepreneur Andrew Torba about two years ago. The site says it now has nearly 800,000 users, meaning that it's tiny compared to Twitter or Facebook.

The site's claim to fame is that users can post almost anything — even if the content is racist — without being sanctioned. It puts nearly no restrictions on content.

In practice, this means it is a favorite of bigots and hate groups. People who get banned from mainstream sites like Twitter for hate speech or harassment sometimes end up on Gab.

"Gab's mission is very simple: to defend free expression and individual liberty online for all people," the site says.

On Saturday evening, some of that free expression translated to shows of support for Bowers. Some commenters even called him a hero. (Those posts were removed later in the evening.)

Gab has been on the defensive before. And it responded again on Saturday by going on offense, criticizing other social networks and arguing (on Twitter) that "the answer to 'bad' speech will always be MORE speech."

According to the company , it "backed up all user data from the account" after the attack happened, "then proceeded to suspend the account. We then contacted the FBI and made them aware of this account and the user data in our possession." Gab said it "unequivocally disavows and condemns all acts of terrorism and violence."

Later in the day, Gab's Twitter account said that someone from the company "just got off the phone with the US Attorney's Office."

Gab said in a tweet that "we are continuing to help with the investigation into today's horrific tragedy and have made every resource we have available in order to see that justice is served and law enforcement has what they need."

A spokesperson for Twitter said, "As of now, they have not done something that violates rules that has been flagged to us. So in that, they're like any other business."

Suspect's anti-Semitism fueled other hate speech on Gab

The criticism of Gab is centered around the content that was allowed to live on the site before the attack.

Bowers' profile on Gab appeared to serve as an echo chamber for that racist, anti-Semitic and bigoted ideology. The content he discovered on the platform not only fueled his beliefs, but it was used to fester new branches of his bigoted ideology through other users' content and citations.

The suspect reposted a number of posts on his social media accounts that tell Jews to get out, or leave.

In recent weeks, Robert Bowers posted photos of his handgun collection on Gab, the social media site.

The suspect's anti-Semitism fueled other hate speech that he shared on Gab. He promoted a conspiracy theory that Jews were helping transport members of the migrant caravans in Central America. He repeatedly called the migrants "invaders," using language that's common on right-wing TV and radio.

"I have noticed a change in people saying 'illegals' that now say 'invaders'," read one post, six days before the shooting. "I like this."

The suspect repeatedly disparaged the Hebrew Immigrant Aid Society, a Jewish refugee support group, by claiming that "HIAS likes to bring in invaders that kill our people." HIAS held a "National Refugee Shabbat" last weekend.

HIAS chief executive Mark Hetfield said on CNN Saturday night that "we're just devastated" by the shooting spree.

"The problem here is hate," Hetfield said. "The problem is, there is a growing space in this country for hate speech. And hate speech always turns into hate actions. And that's what we are seeing again and again this week."

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In the wake of Saturday's shooting, PayPal banned Gab from using its platform to manage donations from users to help support Gab.

"When a site is explicitly allowing the perpetuation of hate, violence or discriminatory intolerance, we take immediate and decisive action," PayPal said in a statement.

Meantime, Gab argued that only one person was to blame for the mass murder: the suspect.

"Words are not bullets. Social media posts have a body count of zero," the company said in a tweet. "The sole responsibility for today's horrific actions lies with one person. We will do everything in our power to work with law enforcement to see that justice is served."