He typed the names of his targets on a spreadsheet: "sheila jackson ... Chris hayes ... ilhan omar." He searched online for the best ways to kill black people and for the addresses of a couple of U.S. Supreme Court justices. By the time federal authorities arrested U.S. Coast Guard Lt. Christopher Hasson at his house in Silver Spring, Md., in February and began to release details of his alleged plot to kill prominent politicians and journalists in court filings, Hasson had been stockpiling weapons for at least a decade.

News of his arrest reached the public in typical fashion, on Twitter. But the source was not typical. Instead of the U.S. Department of Justice or a major media outlet, it was a little-known researcher in Washington named Seamus Hughes.

Hughes, 35, is the deputy director of the Program on Extremism at George Washington University, a research group that collects information about radicalism and terrorism in the United States, then turns it into reports, graphics and other easily digestible forms. It tends to find newsworthy tidbits by accident, rather than by design, according to the program’s director, Lorenzo Vidino. “We don’t want to steal your job,” he said with a laugh when I spoke to him earlier this year. “Because of the work that we do, we come across a lot of interesting information.”

Vidino and Hughes rely on a variety of sources. They mine public databases, passively monitor Islamic State propaganda online and track the group’s members on encrypted messaging apps like Telegram. “[Lorenzo] and I will wake up — at our separate homes — at 5 a.m. and nerd-out on a case or write up a five-page report really quickly because it’s really interesting to us,” Hughes told me one morning in March over his second cup of coffee. “For us, it’s not necessarily a job — it’s much more fun than that. You have a challenge of trying to figure out how to answer the question of why a guy in New York decided to join ISIS.”

A self-proclaimed digger, Hughes is a master of PACER, a database of federal court documents that can be hard to navigate. Hughes happened to be trawling PACER, looking for terrorism-related cases, when he stumbled upon Hasson’s detention memo. When he comes across an interesting case that the program doesn’t have the time or resources to pursue, he turns to Twitter. “We throw it out in the wind and hope The Washington Post or somebody else runs with it,” he says.

Hughes also finds notable cases that are unrelated to the program’s work. For instance, in January, he broke news on Twitter of the FBI’s investigation into Los Angeles City Council member Jose Huizar for bribery and money laundering. While releasing such material isn’t part of his job, doing so is “a welcome respite,” he says. “If you look at beheading videos every day, at some point you’re going to need a break, and that’s part of my break.”

Hughes began investigating terrorism cases in the aughts, first as an intern and later as a staff member for the Senate Committee on Homeland Security and Governmental Affairs. In 2011, he went to work for the National Counterterrorism Center. In 2015, a former Senate colleague introduced him to Vidino, who hired him to work at the newly launched Program on Extremism.

Vidino, 42, started the program after holding positions at Harvard University, the U.S. Institute of Peace and the Rand Corp. “We thought there was an appetite for some nonpartisan research and analysis on extremism, particularly on religiously inspired extremism, looking mostly at the domestic scene,” he says. “Paradoxically, you’ll find a lot of research being done on al-Qaeda and ISIS, but not so much on the process of radicalization of Americans.” The program is funded by foundations, Hughes says, “the Mellons of the world.”

By carving out this niche, the program has become a standout in the close-knit terrorism research community, which includes academic centers and think tanks. Hughes and Vidino have created “an amazing clearinghouse of information ... that puts them in a position where they can be literally the most authoritative voices out there talking about extremism in the United States — and that’s a tremendous resource for the rest of us,” says Nicholas Rasmussen, the senior director for national security and counterterrorism programs at the McCain Institute for International Leadership, a think tank in Washington.

Vidino and Hughes are joined by seven other staffers at GW and oversee more than a dozen nonresident fellows who are scattered across the country. Since the program began, the center’s researchers have uncovered about 20,000 pages of legal documents — pertaining to everyone who’s ever been arrested for international terrorism in the United States — and pulled about 1.5 million English-language tweets about the Islamic State.

Vidino is currently leading a research project in partnership with the New York Times where he’s tasked with digitizing, translating and publishing roughly 15,000 pages of internal Islamic State documents. The project was “very much in line with our focus and expertise and we were naturally happy to partner with them,” Vidino says, adding that the program works with many domestic and international media outlets. He is also a frequent contributor to the BBC.

The program’s research goes beyond documents and social media. It includes interviews with former Islamic State members, relatives of terrorists, FBI agents and attorneys. Encounters with family members of Islamic State militants, in particular, can be difficult and require sensitivity. “You’ve got to put it in context. I’m the parent of two kids, so if I’m sitting across the room from a mother whose son just joined al-Shabab, I can think of myself and how I would feel if my son did the same thing,” Hughes says. “You can’t discount that the individual joined a foreign terrorist organization that’s doing horrible things to a lot of people, but you also can’t discount the human cost of those who are left behind after that decision is made.”

The work could soon become more labor-intensive: Lately, social media platforms have come under fire for not removing extremist content, as happened after a video of the attacks on two mosques in Christchurch, New Zealand, in March was widely shared on Facebook. If the platforms take down this content, Hughes says, they are likely to drive the material to a larger number of smaller sites — an outcome that would create new challenges for researchers. For law enforcement, meanwhile, such a change would probably have both drawbacks and benefits, he explains: “It does make the intelligence and law enforcement jobs more difficult from the standpoint of looking at a target, but probably better from the standpoint of not getting more recruits.”

Will there be more scoops coming from Hughes? Maybe not quite as many, since he is sharing his PACER techniques with more journalists. In the past two months, he has trained more than 500 reporters across the country on how to use the site. And they, in turn, have shared tips on filing Freedom of Information Act requests. “I wasn’t expecting that level of response; it’s been mildly overwhelming,” he says. “And it’s been really interesting to me and quite useful to exchange notes with reporters, because in many ways the tips that they have when it comes to doing investigations are skill sets that I didn’t necessarily have.”

Christina Sturdivant Sani is a writer in Washington.