By David Canfield
March 21, 2018 at 07:02 PM EDT
ABC Photo Archives/ABC via Getty Images

An upcoming biography of Robin Williams features corroborated allegations that the late comic actor displayed sexually inappropriate behavior while on the set of Mork & Mindy, the Daily Mail has revealed.

Particularly, Williams’ former Mork & Mindy costar Pam Dawber says that he harassed her regularly, a claim backed up by director Howard Storm and the late producer Garry Marshall, both of whom were interviewed by author David Itzkoff. “I had the grossest things done to me by him,” Dawber is quoted as saying in the biography, per the Mail. “I never took offense. I mean, I was flashed, humped, bumped, grabbed. I think he probably did it to a lot of people…”

“He’d be doing a paragraph and in the middle of it he would just turn and grab her a–,” Storm added. “Or grab a breast. And we’d start again. I’d say, ‘Robin, there’s nothing in the script that says you grab Pam’s a–.’ And he’d say: ‘Oh, OK.”’ Marshall added that Williams would stand naked opposite Dawber while she was trying to act, in order to make her “blush.”

A spinoff of Happy DaysMork & Mindy ran for four seasons and netted Williams an Emmy nomination. He starred as the alien Mork while Dawber played Mindy, the human who falls in love with and marries him. Dawber seemingly does not have any hard feelings toward Williams; she’s reportedly quoted in the book as saying his behavior was “so much fun” and that “it was the Seventies, after all.”

“If you put it on paper you would be appalled,” she elaborated. “But somehow he had this guileless little thing that he would do — those sparkly eyes. He’d look at you, really playful, like a puppy, all of a sudden. And then he’d grab your tits and then run away. And somehow he could get away with it.”

Storm also noted for the book that Williams behaved this way toward other women on the set. He recalled an incident between Williams and the actress who played Mindy’s grandmother. “I’m standing there watching this and I’m thinking, ‘oh my god’ and I just laughed,” Storm said. “I thought she was going to turn and say: ‘How dare you stick a cane in a woman’s a–?’ That sweet old lady. There was nothing lascivious about it, in his mind. It was just Robin being Robin, and he thought it would be funny. He could get away with murder.”

Williams’ estate did not immediately respond to a request for comment.

Robin will be published on May 15 by Henry Holt. The book also explores his history of addiction and traces his life story, through to his untimely death. You can pre-order Robin here.