From the Kennedy Assassination to Edward Snowden, Edward Jay Epstein has built a career out of challenging the conventional wisdom. The author of several seminal works of investigative journalism is the subject of an arresting new documentary, “Hall of Mirrors,” which premiered at the New York Film Festival this month. It is looking for distribution. The film marks the directing debut of sisters Ena and Ines Talakic, and serves as both a retrospective of Epstein’s fascinating career and a memorial to a type of reporting that has largely fallen out of favor in an era of clickbait headlines.

“He’s just someone who asks basic questions and gets full access to the most incredible people,” said Ines Talakic. “He takes his time and he digs deep.”

That’s been a hallmark of Epstein’s career. As an undergraduate at Cornell he managed to speak to nearly every member of the Warren Commission save for Chief Justice Earl Warren. His resulting book, 1966’s “Inquest: The Warren Commission and the Establishment of Truth,” pulled back the curtain on a shoddy investigation into Lee Harvey Oswald’s motives and methods at a time when the consensus view was the government has left no stone unturned. A long line of Kennedy conspiracy theories can be traced back to the questions “Inquest” raised.

“I like learning,” said Epstein. “I spend years investigating something and over that time you really become an expert.”

Armed with a deep-seeded curiosity, Epstein spent the rest of his career tackling thorny subjects. He wrote one of the early works of media criticism, “News From Nowhere,” after spending four months in the newsroom of NBC, and an additional two months in those of CBS and ABC. Later works such as “The Rise and Fall of Diamonds,” a look at the cartels behind the precious gems, and “Dossier: The Secret History of Armand Hammer,” a biography of the monomaniacal and ethically shady chairman of the Occidental Petroleum Company, were also deeply researched.

But it’s not just unscrupulous moguls and political conspiracies. Epstein has also written lucidly about Hollywood. He’s had a particular fascination and fluidity with the movie business’ economic underpinnings and colorful accounting project. Perhaps it was an earlier failed attempt to produce a film version of the Illiad that interested him in Tinseltown. The 81-year old writer’s next project will look at digital disruption and its impact on the film industry.

The Talakic sisters met Epstein at a party hosted by Nouriel Roubini, the noted economist, and eventually convinced the writer that he would be a good subject for a documentary. They then spent more than four years getting an up close and personal look at Epstein’s methods and archives.

“Ed is fascinating because you realize that he is really a part of history through all of his investigations,” said Ena Talakic. “We found it interesting that someone who just asks basic questions can end up getting full access to people and can convince them to talk to him.”

Over the course of the film, the Talakic sisters follow Epstein as he heads to Hawaii, Hong Kong, and Russia, re-tracing the route that Snowden took as he decided to reveal the inner workings of America’s intelligence gathering operation, and later was forced to seek asylum from Vladimir Putin.

To prove his point that Snowden might have been a spy, Epstein tracked down former neighbors, co-workers, and members of the KGB. The book that emerged from the months of reporting, “How America Lost Its Secrets,” elicited some heated criticism, particularly from journalists such as Glenn Grenwald and Barton Gellman, who broke the initial Snowden pieces.

“How America Lost Its Secrets” debuted in January of 2017. Epstein wonders if the book and its claims about Russia’s designs on Snowden wouldn’t have been more warmly received if it came out a few months later, when Russia was a hot topic. After all, the Kremlin is in the headlines for trying to manipulate the U.S. presidential election, and Putin’s ambitions to influence Western politics have become clearer.

“It’s hard to pretend now that it didn’t matter that Snowden went to Russia,” said Epstein. “The view of Russia at the time was benign. Now it’s demonic.”

“Hall of Mirrors” is very much a celebration of a life well lived and a body of investigative work that has helped shape popular perceptions of government, culture, and commerce. There’s something sad about it, however. It’s a reminder that the kind of reporting that Epstein does — research intensive, meticulous, and wide ranging — is fading. The journalism that is replacing it looks flimsy by comparison.

“There are fewer and fewer outlets for investigative reporting,” said Ines Talakic. “Most people aren’t able to spend the same type of time. People are under so much pressure to rush stories.”

Epstein’s career and writings are a reminder that great reporting shouldn’t be rushed. It takes time to discover the truth.