Alexis Arquette's death certificate shows she had been living with HIV for almost three decades when she died aged 47.
The immediate cause of death was cardiac arrest, but TMZ reports Arquette had also been battling HIV for 29 years.
The certificate filed in LA County shows she had a bacterial infection of the heart for three weeks before she died on September 11.
It has also emerged Arquette was once again living as a man before dying and the death certificate lists male under sex and uses the full name Robert Alexis Arquette.
His former boyfriend Robert Dupont confirmed to Radar Online Arquette had multiple ailments that caused the death, including AIDS.
He said: “Alexis was living with AIDS and he had an inoperable tumor and he had developed an infection.
“I was told that went to his liver and throughout his body.”
Dupont, who was close friends with Andy Warhol, dated Arquette for several years in the 1990s.
He also confirmed Arquette was put in an 'induced coma.'
'He was working as an artist and living in an Actors Fund home in West Hollywood for people with HIV and AIDS.” he revealed.
“He hated it.
“People kept breaking into his apartment and they did alcohol and drugs.
“Alexis hated that. He never did drugs and he didn’t drink.”
Arquette, whose siblings include actors Patricia, David and Rosanna Arquette, died surrounded by oved ones, his brother Richmond wrote on Facebook.
The actor wrote Arquette passed away at 12.32am while listening to David Bowie's Starman.
Paying tribute to Arquette, he said: 'I am feeling immense gratitude to have been afforded the luxury of sharing life with him/her, for learning from Alexis, for being given the gift of being able to love him/her.'
He added: 'Thank you, Alexis, I love you and will love you always.'
He said that he is 'immensely grateful that it was fast and painless.'
Arquette, was born Robert, but transitioned to a woman in 2006. However, Arquette remained tight-lipped about surgery.
'It got to the point when I wasn’t willing to answer the questions about hormones, surgeries, or genitalia because it felt like backstepping,' he told a press conference, according to the Huffington Post in 2011.
'It wasn’t a subject that needs any more exploitation; it needs clarification.'
Arquette, best known for the roles in Pulp Fiction and The Wedding Singer, was also a prominent transgender activist.