Hollywood director George Hickenlooper died of an accidental overdose from prescription drugs, a medical examiner has confirmed.The film-maker, who won an Emmy in 1992 for the film Hearts of Darkness: A Filmmaker's Apocalypse, passed away last month aged 47.
It was originally thought he had died of natural causes.
He had been due to attend a premiere of his latest work, Casino Jack, starring Kevin Spacey and Kelly Preston.
The political thriller was being shown as part of November's Denver Film Festival.
Organisers announced the event would be dedicated to the filmmaker.
Hearts of Darkness (1991) was a well-received documentary about the making of the film Apocalypse Now.
It won several awards including the National Board of Review award for Best Documentary, while Hickenlooper himself won an Emmy for direction.
His other films include Factory Girl, Mayor of the Sunset Strip and the documentary Hick Town, based on footage shot while he followed his cousin around during the 2008 Democratic National Convention.