Lawyers for American billionaire, Elon Musk, have sent a formal legal warning to the producers of a new four-hour documentary about Musk just days before its premiere, arguing the film contains defamatory content. The letter, dated September 3 and sent by attorney Alex Spiro to a producer at Alex Gibney's Jigsaw Productions, accuses the Oscar winning filmmaker of shaping the documentary, titled "Musk," around a conclusion he had already reached rather than conducting an open investigation.

The teaser for Alex Gibney's Elon Musk documentary is here. It promises an "unflinching look at earth's most unchecked man."

Speaking at the Venice Film Festival, award-winning documentarian Alex Gibney reveals the "fear" he found when approaching subjects to take part in his latest movie, a four-hour…