The scoop of a lifetime for George Chidi, a freelance journalist in Georgia, began at the State Capitol on the morning of Dec. 14, 2020, when a longtime source walked briskly past, eyes averted as if he didn’t know him, then disappeared into Room 216.

Mr. Chidi, concluding that something odd was taking place on the other side of the door, turned the knob and stepped into history.

What he saw, and simultaneously live-streamed from his phone, were six to 10 people who reacted with alarm to his presence. As the source, an 18-year-old Republican activist named CJ Pearson, bustled wordlessly out of the room, Mr. Chidi asked what was going on.

“Education,” one of the people said.

Mr. Chidi was soon escorted out of the meeting, but once in the corridor he asked who had reserved the room. Eventually, a clerk informed him that it was the House speaker, David Ralston, a Republican, who had done so at the behest of one of President Donald J. Trump’s lawyers, Ray Smith. An hour or so later, the state’s Republican chairman, David Shafer, stepped out and told a gathering crowd of reporters that he and the others in the room were providing an “alternate” slate of electors favoring Mr. Trump as a means of challenging Georgia’s official 2020 election results.

As of this week, that challenge is characterized as important evidence of a criminal enterprise in a 98-page indictment, the State of Georgia vs. Donald John Trump and 18 other conspirators. It appears on Page 17 under the heading, “Creation and Distribution of False Electoral College Documents.”

Recounting the tableau at a coffee shop in Decatur, Ga., on Tuesday morning, only hours after the indictment was made public at the Fulton County courthouse, Mr. Chidi said he wanted to dispel any notion that his achievement had been a fluke, like a journalistic equivalent of scratching a winning lottery ticket.

“It’s not like I just wandered into the Capitol that day,” Mr. Chidi said. “This was years of reporting.”

Bald, voluble and insomnia-prone, Mr. Chidi, 50, has a nonlinear but relentless career trajectory that offers an object lesson in how local journalism, imperiled though it may be, can achieve national significance.

He is a curious hybrid of old school and new school, an aggressively skeptical journalist but also a man unwilling to remain on the sidelines taking notes. In 2012, he participated in Occupy Atlanta protests that incurred the scorn of Republicans. Five years later, he worked to help close a blighted homeless shelter in the city, to the consternation of some local progressives.

Twice he has lost bids for public office, first for state representative and then for county commissioner. He also served two terms on the City Council of Pine Lake, Ga.

Mr. Chidi currently makes his living from the 300 or so subscribers who pay $10 a month to read his Substack page, called The Atlanta Objective. The title reflects his animating interest, both in civics and as a writer. He describes a city of enduring promise and vexing inequality, in which the average income of a white household is $80,000 — more than double that of a Black household.

In terse but evocative prose and deep reporting, Mr. Chidi examines topics like homelessness and street shootings. He is not shy about contrasting himself with the comparatively polished members of the national press who descended on the Fulton County courthouse to capture the moment of Mr. Trump’s indictment.

The son of a Nigerian-born doctor and a stay-at-home mother of Polish descent, Mr. Chidi spent his adolescence as a nerdy Dungeons & Dragons aficionado, one of the only Black students at his school in Northbridge, Mass. After flunking out of the University of Massachusetts, he joined the Army as a reservist in 1991. A slot for a military journalist opened up. As someone with a few English credits who could type over 20 words a minute, Mr. Chidi qualified.

Beginning in 1995, he spent the next four years with the 25th Infantry Division in Hawaii, a setting that amounted to on-the-job-training for a local reporter.

“Chidi always tested the limits,” recalled Dee McNutt, his former supervising editor at The Hawaii Army Weekly. “He would always try for a different angle, and sometimes I’d have to sit him down and talk to him about it. But he made us better.”

Returning home to the Boston area in 1999, Mr. Chidi struggled to find regular journalism work. He made ends meet as a substitute teacher while moonlighting as a security guard. Finally, in 2004, he landed a reporting job for The Rocky Mount Telegram in Rocky Mount, N.C., which paid $14 an hour. His profiles of migrant workers in the area’s tobacco fields caught the notice of The Atlanta Journal-Constitution, which hired him in 2005. An editor for that newspaper, Bill Torpy, recalled strolling through Centennial Olympic Park with Mr. Chidi just after he accepted the new job.

“George threw his arms in the air, twirled around and yelled, ‘Atlanta!’” Mr. Torpy said.

But the elation proved to be short-lived. Mr. Chidi spent the next two years as a crime reporter, a despairing beat. He said he came to view crime as “a political issue,” one that reflected a city’s social and budgetary choices that all too often came at the expense of a nonwhite underclass. At around the same time, The Atlanta Journal-Constitution ceased its practice of endorsing political candidates, which Mr. Chidi interpreted as the paper’s reluctance to risk offending readers during a challenging time for local journalism.

“I think he just got tired of it,” Mr. Torpy said. “When you’re working for a newspaper, you’re there to report, and you can’t be an activist. He needed to be where there’s no wall separating the two. And that’s where he is now.”

As a self-described independent journalist, Mr. Chidi’s work often takes him to the State Capitol. He was there on Dec. 19, 2016, videotaping demonstrators who marched outside the building while the state’s 16 electoral votes for Mr. Trump were being tallied.

Four years later, Mr. Chidi anticipated that the 2020 electoral certification would be far less placid. He attended a “Stop the Steal” rally in which the right-wing personalities Alex Jones, Ali Alexander and Nicholas Fuentes spoke from the Capitol steps and then, the next day, from inside the building. Mr. Chidi recognized many of the attendees as members of far-right local militia groups he had seen squaring off with antiracist protesters months earlier in Stone Mountain, where Mr. Chidi lived.

It was with those encounters in mind that he made his way back to the State Capitol on Dec. 14, 2020.

Asked the morning after Mr. Trump’s indictment whether he would now leave the story to the national press, Mr. Chidi put down his cup of coffee and thought for a moment.

“Hell, no,” he said. “I want to compete with those guys. Come to my home turf and see what happens.”