As a reporter in the 1990s, C. Justin Brown filed stories as a war correspondent in Kosovo and as a national security correspondent for the Christian Science Monitor. He was published in The New York Times and Newsweek, and was nominated for a Pulitzer Prize. But he penned what might be one of his most-read pieces in June 2015, long after he traded in his journalism bona fides for a law license.

It was a motion to reopen post-conviction proceedings, written on behalf of a client found guilty of murder in 2000. The reason it was so popular? The client in question is Adnan Syed, the central figure of the wildly popular NPR podcast, Serial, which sought to take a closer look at Syed’s arrest and conviction for the 1999 murder of his high school ex-girlfriend, Hae Min Lee.

“I would bet that motion was probably read by more people than any motion to reopen post-conviction ever,” says Brown, who works out of his eponymous firm in Baltimore. “People are commenting on Twitter, ‘Wow, footnote five on page nine was awesome.’ It’s kind of cool, but it’s also kind of nerve-wracking. Everything I do is under a microscope.”

The motion centers on Brown’s contention that Syed didn’t receive constitutionally effective representation from counsel during the trial; specifically, that the lawyer never contacted a crucial potential alibi witness, Asia McClain—the high school classmate who says she saw Syed in a public library when the murder happened.

“I believe in [the McClain alibi],” he says. “There have been all these other issues that have come and gone, but I’ve always thought that that one was going to be the one that would get the conviction reversed.”

Long before the world started obsessing over cellphone records and possible alibi witnesses of Baltimore teenagers, Syed was something of a typical post-conviction client for Brown, who had built a reputation for that type of work at Nathans & Biddle in the mid-2000s. Syed’s family hired him in late 2009, as the 10-year deadline for filing a post-conviction motion was fast approaching.

“It was probably filed exactly 10 years after the sentencing,” Brown says. “The clock was ticking.”

At the following hearing, the circuit court judge ruled against Syed. That’s usually the end of the line for post-conviction clients; Brown filed an application for leave to appeal, but it was a long shot. According to Brown, over a recent five-year span, only 13 of 1,058 applications were granted—a success rate of just over 1 percent.

“For all intents and purposes, we had lost,” he says. “It was dead, which was incredibly depressing. Anytime someone is serving a life sentence and you're their last line of defense, it's an awesome responsibility. Statistically, the odds of you succeeding are very slim.”

It was a combination of those what-do-we-have-to-lose odds and professional courtesy that led Brown to agree to meet with Sarah Koenig in spring 2014. Koenig, the producer and host of the project that would become Serial, reached out to Brown because she was interested in doing a piece on Syed, a segment Brown figured would be some kind of one-off radio report. “I went and met her at a Starbucks,” he says. “I largely [went] because she’s a journalist. I wanted to be polite. Little did I know how big this whole thing would blow.”

How big? CNN reported that in December 2014 alone—two months after Serial’s October premiere—39 million Americans tuned in; it went on to win a Peabody Award in 2015, a first for a podcast.

Once Serial became a phenomenon, Brown recognized it for the opportunity it presented.

“It has definitely helped us,” he says. “There is no doubt about that. Most immediately, it brought Asia McClain to us. Essentially, we could not produce her for the post-conviction hearing. I believe that hurt us at the hearing. As a result of Serial, Asia McClain eventually reached out to us and we learned all these things about why she had not been present at the post-conviction hearing”—including, he says, that a state prosecutor convinced her not to participate—“that we otherwise would have never found out.”

On Feb. 6, the state Court of Special Appeals approved the application for leave to appeal, creating the possibility that post-conviction proceedings could be reopened, and leading to Brown’s much-read motion. For fans of Serial’s first season (structured as an anthology, the second season will reportedly focus on the Bowe Bergdahl case), it’s the latest plot twist. But for Brown, it’s another leg of the marathon.

“I can literally open my door right now and there’s a stack of boxes” of documents related to the case, Brown says. “It’s been a long rollercoaster ride.”

The rollercoaster ride just got longer: On Nov. 6, Judge Martin P. Welch granted Syed post-conviction proceedings, a major legal victory for Brown and Syed.

“This is a big development for us,” Brown says. “It brings us one step closer to our goal of winning a new trial for Adnan. I’ve been handling this case for so long, it seems like it’s been forever. I get a lot of people calling: ‘I haven’t seen you in years. Want to grab lunch?’ All they want to do is [hear] about Syed. It’s been a wild ride.”