Novelist Michael Chabon has issued a lengthy apology for not speaking up sooner about producer Scott Rudin’s abuses, saying that he witnessed Rudin mistreat his staff but kept quiet about it because he accepted that was how Hollywood worked.

“I’m ashamed,” Chabon wrote on Medium. “I regret, and I want to apologize for, my part in enabling Scott Rudin’s abuse, simply by standing by, saying nothing, looking the other way.”

Rudin produced “Wonder Boys,” an adaptation of Chabon’s novel, and worked with him on a never-realized adaption of “The Amazing Adventures of Kavalier and Clay,” the novel for which Chabon won the Pulitzer Prize. He also optioned Chabon’s first script, “The Gentleman Host,” in 1994.

Chabon is among the highest profile figures to criticize Rudin since the Hollywood Reporter published a cover story documenting his abuses on April 7. On Thursday, Vulture added to the record, relaying accounts from 33 former assistants and interns who worked at Scott Rudin Productions.

In the Medium essay, Chabon said he was particularly affected to learn of the suicide of Kevin Graham-Caso, who had worked as an assistant for Rudin in 2008-09.

“I remember Kevin Graham-Caso — he was a sweetheart — and it was a gut-punch to learn, from his brother David’s recent video, about his suicide, following years of struggle with PTSD,” Chabon wrote. “I regret most of all that Kevin Graham-Caso is not here for me to tell him personally how sorry I am.”

Chabon had a 20-year professional relationship with the producer, which came to an end after Rudin hurled a volley of insults at him over the terms of a deal.

He said that he knew Rudin’s reputation as a bully from his first meeting with him, but accepted his conduct, as others seemed to, as part of life in Hollywood.

“So I didn’t just know; I took it for granted, from the first,” Chabon wrote. “Scott was the way he was, Hollywood was the way it was, and to be a professional, to be a grown up in Hollywood, you could not take Scott’s behavior too seriously, even when it was unprofessional and juvenile. But that was just bullshit.”

He also said he lacked the vision and the courage to call out Rudin’s behavior.

“Like so many but, thank God, not all of us, I left that feat of public bravery for other — less privileged — people to enact,” Chabon wrote. “I’m grateful to them, and I hope, but have no right to expect, that they’ll forgive me for my passivity and participation in the interlocking systems of dysfunction, bias and abuse that make, enable, reward and, worst of all, glorify the behavior for which, thanks to their courage, Scott Rudin is now being called to account.”