A White supremacist was arrested in Florida in mid-September for making online threats against Black city council candidate in Charlottesville, Virginia. To casual observers this looked like a singular arrest in Trump’s America. But experts who watch the militant end of the fascist movement—including myself—are paying close attention to the fate of Daniel McMahon, 31. The arrest comes after the Department of Homeland Security finally affirmed the threat of “racially based violent extremism.”

McMahon, a self-proclaimed fascist whose online aliases include “Jack Corbin” and “Pale Horse,” harassed progressive activists for years. He specialized in terrorizing women and attacked people of color, LGBTQ people, feminists, Jews and antifascist activists.

On September 18, McMahon was arrested on federal charges in Brandon, Florida, at the house where he lived with his parents. In a press statement, the civil rights division of the Department of Justice (DOJ) reported that McMahon had been charged with “willful interference with a candidate for elective office, bias-motivated interference with a candidate for elective office, threats to injure in interstate commerce, and cyberstalking.”

The charges are related to his January 2019 harassment against Don Gathers, co-founder of the Charlottesville Black Lives Matter chapter and an advocate of relocating Confederate statues. Gathers told the press that he was postponing his campaign for health reasons. But he never returned to the race.

According to the Tampa Bay Times, McMahon’s actions were so extreme that his own mother told the Tampa FBI Joint Terrorism Task Force that she was worried that he would become a mass shooter. Her comments were introduced at his hearing on September 23, where he was denied bail.

McMahon had repeatedly advocated killing people he didn’t like, in addition to genocide and rape. And he was known for spreading personal information about his targets, such as their pictures and home addresses.

McMahon was a prolific poster on Gab, which is, essentially, a racist version of Twitter. There, concerning one woman of color, he said, “Fuck that wetback. Too bad the ICE Agent didn’t shove his fist up her cunt and rip out her womb.” On Discord, a chat platform designed for online gamers that White supremacists frequently use for internal communications, he said a “white girl with a nigger” was “beastilaty” [sic]. On Gab he also wrote, “It’s impossible to rape a female Leftist, because they are so slutty they will sleep with everyone.” He has also been obsessed with me for years; in one of his less profane posts on Gab, he called me the “most evil Jew in the USA.”

Until his arrest, Gab did nothing to stop his stream of threats. Since his arrest his Gab account seems to have been canceled.

One female journalist whom he threatened extensively told me that McMahon repeatedly messaged her calling her a race traitor and suggesting she could be “cured” by having sex with him. The reporter, who requested that I not use her name in an effort to avoid threats from McMahon’s supporters, told me, “It’s obviously jarring and intrusive and threatening to be going about your day and have this seemingly violent and deranged man discussing these sexually violent things. McMahon was determined to make sure his threats had the intended effect of instilling fear and uncertainty in his victims.”

McMahon didn’t just threaten his enemies; also threatened other White supremacists. Scott Ernest, a former White supremacist who knew McMahon several years ago, said that in 2013 McMahon had threatened to rape the twin daughters of famous White supremacist activist April Gaede because of a personal dispute.

Many dark corners of the internet are undoubtedly filled with Daniel McMahons, but it was his tie to Robert Bowers that made his threats carry weight. In September 2018, Bowers killed 11 people at the Tree of Life Synagogue in Pittsburgh. He had criticized a pro-refugee group with a connection to the synagogue, the Hebrew Immigrant Aid Society (HIAS), saying on Gab that “It’s the filthy EVIL jews [sic] Bringing the Filthy EVIL Muslims into the Country!!” And in a Gab post, the morning of the attack, he said “I can’t sit by and watch my people get slaughtered. Screw your optics, I’m going in.”

The Southern Poverty Law Center (SPLC) showed that the person Bowers interacted with most online was McMahon. On Gab, McMahon claimed he didn’t have anything to do with the attack, “but I will say he has more balls than most of you all. God bless that man.”

Nonetheless, for years McMahon functioned without repercussions, other than bans from Facebook and Twitter. The journalist mentioned above said, “he was also practiced enough to know how to avoid wording them in such a way that he would face consequences.”

After many years, the mainstream social media companies—like Twitter and Facebook—are cracking down on overt White supremacists. This has made their more openly bigoted users migrate to niche platforms run by companies that only censor content when they are legally obligated to. Gab is a favorite for racists, but the platform must obey U.S. laws. The more extreme people who seek to openly call for terrorism tend to congregate on Telegram. This platform is so hands-off that it was a favorite for ISIS.

After many years of sticking their head in the sand, it looks like both the FBI and the Department of Homeland Security (DHS) have finally decided to pay attention to White supremacists. In July, FBI director Chris Wray told Congress that most domestic extremism arrests since October 2018* were of White supremacists. DHS has taken a stronger stance. In September, they issued a new “Strategic Framework for Countering Terrorism and Targeted Violence,” which specifically names “White supremacist violent extremism” as a primary threat.

The slew of arrests following the August 3 El Paso Walmart massacre shows the (grossly belated) commitment from law enforcement is real. For example, starting in August, the FBI has arrested four members of Atomwaffen Division and Freukreig Division, two groups that openly advocate a campaign of terrorism. McMahon’s arrest, announced on September 18, appears to be an important piece in this crackdown.

There is a strong argument for this change of attention. The Anti-Defamation League reported in 2018 that all 50 murders in the United States related to political “extremism” had a link to the far right.

But the clock is ticking. Radical movements typically have boom-and-bust cycles, and often split into “mainstream” and “militant” factions as their burst of popularity declines. And so it is with the alt-right.

A significant portion of the White supremacist milieu, of which the alt-right is a major part of, has decided that holding public demonstrations and engaging in legal political work is a dead end. Instead, they have opted for a politics of terrorism. They follow a theory called “accelerationism”—essentially that things must get worse before they get better. So, these fascists are dedicated to making things worse. On Gab, McMahon called himself “a super-accelerationist.” Back on Telegram, after his arrest, his colleagues voiced their support for him.

As such, McMahon named targets and called for action. Even though his charges are relatively minor—the most he would serve is 12 years if he ‘s convicted of all four—a conviction will no doubt tamper his colleagues’ online enthusiasms.

One journalist who was harassed by McMahon told me, “I was surprised that he was charged, but I felt a huge sense of relief. There are a lot of Daniel McMahons out there right now who haven’t faced consequences. I think his arrest should send a ripple of fear throughout the movement, a message that maybe you can’t get away with this kind of behavior indefinitely.”

If law enforcement agencies and social media platforms had cracked down years ago on the threats, the pro-terrorism White supremacists could have been dispersed before their networks congealed. Those of us who tried to “ring the alarm” about rising White supremacist violence were largely ignored. And even after the deadly Unite the Right rally in Charlottesville, the mainstream dragged its feet into taking action. We can see this as it’s taken two years since Charlottesville—and several additional massacres—for federal law enforcement to focus on White supremacists.

Looking at attacks worldwide, there have been six since October 2018 that are these closely linked, with online fascist networks copying and referencing each other. The three attacks that occurred in the U.S.—in Pittsburgh, El Paso and Poway, California—have claimed the lives of 34 people.

In McMahon’s case, his lawyer says he “categorically denies all of the allegations” against him. At a hearing on October 16 in Charlottesville, McMahon pled not guilty.

His trial date is set for December 23.

Spencer Sunshine writes about the contemporary U.S. far right. Follow him on Twitter: @transform6789.

*Piece has been updated to correct a date.