Bart Layton's 2012 portrait of a French con artist who convinced a Texas family he was their missing son. Documentary as thriller.
From Wikipedia
The Imposter is a 2012 documentary film about the 1997 case of a French confidence trickster Frédéric Bourdin, who pretended to be Nicholas Patrick Barclay, an American boy who had disappeared in Texas at the age of 13 in 1994. The film was directed by Bart Layton. It mainly includes interviews with Bourdin but also with members of Barclay's family, as well as archive television news footage and reenacted dramatic sequences.