Hugh Hefner died of respiratory failure following a cardiac arrest, it has been revealed.
The official death certificate, released by the Los Angeles Department of Public Health, also noted he had been battling e. coli and septicaemia for six days before his death.
"The e.coli strain he had was so severe, it was highly resistant to antibiotics," website The Blast, which first published the death certificate, reported.
The Playboy founder passed away at his LA mansion last Thursday. He was 91 years old.
His death was met with countless online features surmising his polarising legacy, with some praising his role in promoting the sexual revolution of the '50s and '60s and defending free speech and civil rights, while others criticised his magazine's exploitation of women.
On Wednesday, it was announced that Jared Leto would be portraying Hefner in a new biopic from director Brett Ratner.
Ratner's production company RatPac Entertainment - co-founded by James Packer, who remained a co-owner until he sold his share to Access Entertainment in April - will develop the project, which has been in the works since 2007. Robert Downey Jr was previously attached to the role.
"When [Leto] heard I got the rights to Hef's story, he told me, 'I want to play him. I want to understand him'," Ratner told Hollywood Reporter.
"And I really believe Jared can do it. He's one of the great actors today."
The director said he'd even taken Leto to meet Hefner around the time of his 91st birthday celebrations in April, but Hefner was already in failing health and unable to take guests.
"There's enough footage on Hef out there that Jared will be able to get as much information as he wants," Ratner told Hollywood Reporter.
Hefner's controversial life was recently covered in the Amazon docu-series American Playboy, starring New Zealand actor Matt Whelan as the young publisher.
The Playboy founder himself had also cameoed on numerous TV shows well into his later years, including Entourage, Sex and the City, and his own E! reality series The Girls Next Door and its subsequent spin-offs.