Born Robert Arquette, Alexis started acting at age 12, and went on to earn roles in the Bride of Chucky, Of Mice and Men, and played a Boy George impersonator in The Wedding Singer, among others. Alexis documented her transition to a woman in the 2007 film, Alexis Arquette: She's My Brother.
"Our brother Robert, who became our brother Alexis, who became our sister Alexis, who became our brother Alexis, passed this morning September 11, at 12:32 am," Richmond posted on Facebook. "He was surrounded by all of his brothers and sisters, one of his nieces and several other loved ones. We were playing music for him and he passed during David Bowie's Starman. As per his wishes, we cheered at the moment that he transitioned to another dimension."
Richmond's agent confirmed to PEOPLE that Alexis had indeed died.
Patricia tweeted the video for "Starman" early Sunday morning, with the caption, "Breaking through the veil singing Starman."
She also tweeted out "Cosmic Dancer" by T.Rex, adding, "To My first best friend – Cosmic Dancer".
"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 and to be loved by him/her. He was a force," Richmond continued.
"He died as he lived, on his own terms. I am immensely grateful that it was fast and painless. It was an incredibly moving experience and I am humbled and grateful to have been able to have been with him as he began his journey onward."
"Thank you, Alexis, I love you and will love you always."
Alexis' most recent role was in 2014's Blended.