Hugh Hefner’s butler has released a memoir he wrote four decades ago about his time working for the Playboy publisher, Variety reports.

Stefan Tetenbaum’s The Dark Secrets of Playboy was published by Around the Way Publishing. In the book, Tetenbaum claims that Hefner hired sex workers and mistreated women.

“My story at the Playboy Mansion West during the peak years [of] 1978-80s was an extraordinary period of Playboy Enterprises’ power and fame,” Tetenbaum told Variety. “Working alongside Hefner gave me incredible insight into the daily life and times of such a complex man and the world he created. It was his world—private and hidden.”

Hefner, who died in 2017, was one of America’s most recognizable celebrities, known for his louche lifestyle and propensity for young girlfriends. Earlier this year, A&E aired a documentary series, Secrets of Playboy, in which some women accused Hefner of bestiality and sexual assault.

Tetenbaum said his book explores the “dark underbelly” of Hefner’s life.

“I was not able to publish this book until now because the publishing world could not take a risk with such a giant figure in the media world,” Tetenbaum said. “Hefner had tremendous power to stop anyone looking to tell this story. No one could believe these hair-raising stories then and a certain group of loyalists to Hefner still can’t believe that this world of power and abusive manipulation was true.”

Michael Schaub is a Texas-based journalist and regular contributor to NPR.