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It has long been common wisdom in certain parts of the Bronx that the muscular, tattooed man named John Rezaj should be referred to as “John” or “J.R.,” or maybe, if speaking with admiration about his approach to night life, “the Albanian Keith Richards.” One should not under any circumstances call him “an Albanian gangster.”

Yet Mr. Rezaj, a 49-year-old immigrant whose family fled Albania when he was a boy, has friends and associates across a wide breadth of social circles, some of them less consistently observant of state and federal laws than others. So in 2016, he was happy to help a young filmmaker who wanted to learn more about Albanian gangsters.

The two met on many occasions in Albanian bars and social clubs, where Mr. Rezaj and others talked about old times. Through these conversations, the filmmaker, Matthew A. Brown, started to develop a fictional story about an Albanian gangster. Then one day, Mr. Brown asked Mr. Rezaj a big question: Would he play the main character?

Now the film is complete and has been making the festival rounds, even while its backers are still looking for a distributor. Its improbable star, who has had no acting training and has spent most of his adult life avoiding both the spotlight and daylight in general, has found himself schmoozing with industry people at film gatherings and posing for selfies with fellow countrymen who have heard about the movie.