Photographer/author Mark Thompson recently died at his home in Palm Springs, California. He was 63.

The Riverside County Coroner’s office has said an investigation into the cause of death is pending, with a toxicology report expected in a few weeks.

Thompson was a former senior editor at The Advocate, and edited a book on the publication’s history called Long Road to Freedom: The Advocate History of the Gay and Lesbian Movement. Among some of his other works are Gay Spirit: Myth and Meaning, Gay Soul: Finding the Heart of Gay Spirit and Nature, and Gay Body: A Journey Through Shadow to Self.

He was an early gay-rights advocate, co-founding the Bay Area-wide Gay Students Coalition and starting a gay student publication while attending San Francisco State University in 1973.

Thompson’s partner, Malcom Boyd, died last year. They met in 1984 and legally married in 2013.