The email arrived just as Megan Squire was starting to cook Thanksgiving dinner. She was flitting between the kitchen, where some chicken soup was simmering, and her living room office, when she saw the subject line flash on her laptop screen: “LOSer Leak.” Squire recognized the acronym of the League of the South, a neo-­Confederate organization whose leaders have called for a “second secession” and the return of slavery. An anonymous insider had released the names, addresses, emails, passwords, and dues-paying records of more than 4,800 members of the group to a left-wing activist, who in turn forwarded the information to Squire, an expert in data mining and an enemy of far-right extremism. View more Fingers tapping across the keyboard, Squire first tried to figure out exactly what she had. She pulled up the Excel file’s metadata, which suggested that it had passed through several hands before reaching hers. She would have to establish its provenance. The data itself was a few years old and haphazardly assembled, so Squire had to rake the tens of thousands of information-filled cells into standardized sets. Next, she searched for League members near her home of Gibsonville, North Carolina. When she found five, she felt a shiver. She had recently received death threats for her activism, so she Googled the names to find images, in case those people showed up at her door. Then she began combing through the thousands of other names. Two appeared to be former South Carolina state legislators, one a firearms industry executive, another a former director at Bank of America. Once she had a long list of people to investigate, Squire opened a database of her own design—named Whack-a-Mole—which contains, as far as anyone can tell, the most robust trove of information on far-right extremists. When she cross-checked the names, she found that many matched, strengthening her belief in the authenticity of the leak. By midafternoon, Squire was exchanging messages via Slack with an analyst at the Southern Poverty Law Center, a 46-year-old organization that monitors hate groups. Squire often feeds data to the SPLC, whose analysts might use it to provide information to police or to reveal white supremacists to their employers, seeking to get them fired. She also sent several high-profile names from the list back to the left-wing activist, who she knew might take more radical action—like posting their identities and photos online, for the public to do with what it would.1 Sean Freeman Squire, a 45-year-old professor of computer science at Elon University, lives in a large white house at the end of a suburban street. Inside are, usually, some combination of husband, daughter, two step-children, rescue dog, and cat. In her downtime she runs marathons and tracks far-right extremists. Whack-a-Mole, her creation, is a set of programs that monitors some 400,000 accounts of white nationalists on Facebook and other websites and feeds that information into a centralized database. She insists she is scrupulous to not break the law or violate Facebook’s terms of service. Nor does she conceal her identity, in person or online: “We shouldn’t have to mask up to say Nazis are bad. And I want them to see I don’t fit their stereotypes—I’m not a millennial or a ‘snowflake.’ I’m a peaceful white mom who definitely doesn’t like what they’re saying.” Though Squire may be peaceful herself, among her strongest allies are “antifa” activists, the far-left antifascists. She doesn’t consider herself to be antifa and pushes digital activism instead of the group’s black-bloc tactics, in which bandanna-masked activists physically attack white supremacists. But she is sympathetic to antifa’s goal of silencing racist extremists and is unwilling to condemn their use of violence, describing it as the last resort of a “diversity of tactics.” She’s an intelligence operative of sorts in the battle against far-right extremism, passing along information to those who might put it to real-world use. Who might weaponize it. As day shifted to evening, Squire closed the database so she could finish up cooking and celebrate Thanksgiving with her family and friends. Over the next three weeks, the SPLC, with help from Squire, became comfortable enough with the information to begin to act on it. In the shadowy world of the internet, where white nationalists hide behind fake accounts and anonymity is power, Whack-a-Mole was shining a searchlight. By mid-December, the SPLC had compiled a list of 130 people and was contacting them, to give them a chance to respond before possibly informing their employers or taking legal action. Meanwhile, the left-wing activist whom Squire had separately sent data to was preparing to release certain names online. This is just how Squire likes it. Hers is a new, digitally enabled kind of vigilante justice. With no clear-cut rules for just how far a citizen could and should go, Squire has made up her own. João Canziani

Squire grew up near Virginia Beach in a conservative Christian family. She has been involved in left-leaning movements since she was 15, when her high school environmental club took a trip to protest the pollution from an industrial pig farm. “I loved the activist community,” she says, “and saying things we weren’t supposed to say.” After getting degrees in art history and public policy from William & Mary, she became interested in computers and took a job as a secretary at an antivirus software company, working her way up to webmaster. She eventually got a PhD in computer science from Nova Southeastern University in Florida and moved to North Carolina to work at startup companies before landing a job teaching at Elon. Between classes she could often be spotted around town waving signs against the Iraq War, and in 2008 she went door to door campaigning for Barack Obama. But Obama’s failure, in her view, to live up to his rhetoric, compounded by the Great Recession, was “the turning point when I just threw in the towel on electoral politics,” she says. She plunged into the Occupy movement, coming to identify as a pacifist-anarchist, but she eventually became disillusioned with that as well when the movement’s “sparkle-fingers” utopianism, as she puts it, failed to generate results. In 2016, she cast a vote for the Green Party’s Jill Stein. Donald Trump’s campaign, though, gave Squire a new sense of mission: “I needed to figure out what talents I had and what direct actions I could do.” When a mosque in the nearby city of Burlington was harassed by a local neo-Confederate group called Alamance County Taking Back Alamance County, she decided to put her skills to use. ACTBAC was using Facebook to organize a protest against the opening of the mosque, so Squire began scraping posts on the page that threatened to “kick Islam out of America.” She submitted her findings to the SPLC to get ACTBAC classified as a hate group, and to the North Carolina Department of the Secretary of State, which started an investigation into the group’s tax-exempt nonprofit status. She also organized a counterprotest to one of the group’s rallies, and it was at this event and others like it where she first became acquainted with the black-clad antifa activists. She was impressed. “They were a level of mad about racism and fascism that I was glad to see. They were definitely not quiet rainbow peace people.” Over the following months, she began feeding information to some of her new local antifa contacts. As white pride rallies intensified during 2017’s so-called Summer of Hate—a term coined by a neo-Nazi website—Squire began to monitor groups outside of North Carolina, corresponding with anonymous informants and pulling everything into her growing Whack-a-Mole database. Soon, in her community and beyond, antifa activists could be heard whispering about a new comrade who was bringing real, and potentially actionable, data-gathering skills to the cause. The first big test of Whack-a-Mole came just before the white supremacist Unite the Right rally in Charlottesville on Saturday, August 12. In the weeks before, because of her database, Squire could see that nearly 700 white supremacists on Facebook had committed to attend the rally, and by perusing their posts, she knew they were buying plane tickets and making plans to caravan to Charlottesville. Her research also showed that some of them had extensive arrest records for violence. She sent a report to the SPLC, which passed it on to Charlottesville and Virginia law enforcement. She also called attention to the event on anarchist websites and spread the word via “affinity groups,” secret peer-to-peer antifa communication networks. “Antifa was a level of mad about racism and fascism that I was glad to see. They were definitely not quiet rainbow peace people.” The night before the rally, Squire and her husband watched in horror on the internet as several hundred white supremacists staged a torch-lit march in Charlottesville to protest the removal of a statue of Robert E. Lee, chanting “Jews will not replace us!” The next morning, the couple got up at 5 am and drove more than 150 miles through rain and mist to Virginia. At a crowded park, she met with a half-dozen or so activists she knew from North Carolina, some of them antifa, and unfurled a banner for the Industrial Workers of the World. (She’d joined the Communist-inspired labor organization in December 2016, after witnessing what she considered its well-organized response to KKK rallies in North Carolina and Virginia.) Just before 10 am, the white supremacists began marching into Emancipation Park, a parade of Klansmen, neo-Nazis, militia members, and so-called alt-right adherents, armed with everything from homemade plexiglass shields to assault weapons. Squire screamed curses at the white supremacists by name—she knew them because she had their information on file in Whack-a-Mole and had memorized their faces. At one point, a group of clergy tried to blockade the white supremacists, and Squire linked arms with other activists to protect them. A petite woman, she was pushed aside by men with plexiglass shields. Fights broke out. Both sides blasted pepper spray. Squire put on a gas mask she’d been carrying in a backpack, but the pepper spray covered her arms, making them sting. After the police finally separated the combatants, Squire and dozens of other counter­protesters took to Fourth Street in triumph. But then, a gray Dodge Challenger tore down the street—and rammed into their backs. The driver, who had marched with the white nationalists and was later identified as James Alex Fields, missed Squire by only a few feet. She stood on the sidewalk, weeping in shock, as the fatally injured activist Heather Heyer lay bleeding in the street. Recounting the event months later, Squire began to cry. “I had all this intelligence that I hadn’t used as effectively as I could have. I felt like I’d wasted a chance that could have made a difference.” When she returned home, she threw herself into expanding Whack-a-Mole. Daniel Hosterman

One morning in December, I visited Squire in her small university office. She had agreed to show me the database. First she logged onto a foreign server, where she has placed Whack-a-Mole to keep it out of the US government’s reach. Her screen soon filled with stacks of folders nested within folders: the 1,200-plus hate groups in her directory. As she entered command-line prompts, spreadsheets cascaded across the screen, each cell representing a social media profile she monitors. Not all of them are real people. Facebook says up to 13 percent of its accounts may be illegitimate, but the percentage of fakes in Squire’s database is probably higher, as white nationalists often hide behind multiple sock puppets. The SPLC estimates that half of the 400,000-plus accounts Squire monitors represent actual users. Until Whack-a-Mole, monitoring white nationalism online mainly involved amateur sleuths clicking around, chasing rumors. Databases, such as they were, tended to be cobbled together and incomplete. Which is one reason no one has ever been able to measure the full reach of right-wing extremism in this country. Squire approached the problem like a scientist. “Step one is to get the data,” she says. Then analyze. Whack-a-Mole harvests most of its data by plugging into Facebook’s API, the public-facing code that allows developers to build within Facebook, and running scripts that pull the events and groups to which various account owners belong. Squire chooses which accounts to monitor based on images and keywords that line up with various extremist groups. Most of the Whack-a-Mole profiles contain only basic biographical sketches. For more than 1,500 high-profile individuals, however, Squire fills out their entries with information gleaned from sources like the SPLC, informers, and leaks. According to Keegan Hankes, a senior analyst at the SPLC, Squire’s database “allows us to cast a much, much wider net. We’re now able to take a much higher-level look at individuals and groups.” In October, after a man fired a gun at counterprotesters at a far-right rally in Florida, SPLC analysts used Squire’s database to help confirm that the shooter was a white nationalist and posted about it on their blog. Because so much alt-right digital data vanishes quickly, Whack-a-Mole also serves as an archive, providing a more permanent record of, say, attendees at various rallies. Squire’s database has proven so useful that the SPLC has begun laying the groundwork for it to feed directly into its servers. Mark Peterson/Redux