The 2012 documentary, The Imposter, is up on Youtube in its entirety. It is a truly unbelievable story.
Videos ain't your thing? Here's The Chameleon, the original David Grann New Yorker article from 2008, which is the first time I'd heard of imposter Frédéric Bourdin. If you're unfamiliar with David Grann, he's the author of the Killers of the Flower Moon, which Scorsese filmed in 2023.
Absolutely mind-boggling.
The Telegraph did an interview with Bourdin upon the film's release.