Whether a hoax or not, a new documentary about Joaquin Phoenix and his transition from acclaimed, brooding actor to bearded, shambolic hip-hop wannabe has captivated viewers at the Venice film festival.
"I'm Still Here" was directed by Casey Affleck, a successful actor and Phoenix's brother-in-law.
The guessing game over whether the picture was genuine documentary or ironic "mockumentary" poking fun at an intolerant and narrow-minded public and press began long before the release of the movie.
It mirrors internet chatter following Phoenix's now infamous television interview with David Letterman last year, when a confused, mumbling performance also prompted suspicions that it was all an elaborate act.
"I can tell you that there is no hoax," Affleck told reporters after his directorial debut was screened to reporters on Monday in Venice, where it is out of competition.
"That never even entered into my consciousness until other people began to talk about the movie," he added at a briefing where he was asked repeatedly about whether certain scenes, and the movie in general, were genuine.
But he conceded that audiences were likely to be confused.
"I'm very interested to hear those sorts of reactions and I appreciate that point of view, and I understand how a lot of this movie could be confusing in terms of, 'oh well, it seems like something's real or not real'."
Affleck said Phoenix was in Venice, but was unsure whether he would turn up at the red carpet premiere later in the day.
Candid cameraWhether real or not, I'm Still Here offers a sometimes excruciating insight into the life of a celebrity and into the mind of Phoenix.
He is at times funny and coherent and at others childish, aggressive and paranoid as he struggles to live with his decision in 2008, which the media greeted with breathless disbelief, to give up acting and take up hip hop.
After his Letterman appearance, Phoenix clasped his head in frustration at how badly it went.
"I'm just going to be a god damned joke forever," he said, before launching into an expletive-ridden tirade and bursting into tears.
The candid film includes footage of him apparently taking drugs, surfing the internet for call girls, hosting prostitutes, diving off a stage to attack a heckler and vomiting.
It also features rap star Sean Combs, who, after several failed attempts on Phoenix's part to set up a meeting, agrees to listen to a demo of his hip-hop music.
Comb's face as he listens to three demo tracks is one of the movie's highlights, and Phoenix leaves crestfallen when Combs makes clear he will not produce his record.
Again, though, reporters asked whether Combs was in on the joke. Affleck replied: "The role that he played in Joaquin's life was to be the bearer of bad news. He was the hammer that crushed the dream. All of that is a little bit of an act."
Comedian Ben Stiller also appears when he comes to Phoenix's home to ask him to consider playing a part in his recent movie "Greenberg."