Just in case you thought Donald Trump was insufficiently awful: He repeatedly called a deaf actress “retarded,” three sources tell The Daily Beast.

Trump, who was accused on Wednesday of making sexual comments to Marlee Matlin, an Oscar-winning actress who once competed on Trump’s Celebrity Apprentice, also apparently had a habit of insulting, mimicking, and demeaning as mentally handicapped his star female contestant—all because she was deaf.

In 2011, Matlin, who is still the only deaf actor or actress to win an Academy Award for best actress, appeared on Trump’s NBC reality-TV series. By the end of the season, she had come in second place and earned her fair share of compliments from Trump in the aired footage. But according to three longtime staffers who worked on Matlin’s season of Celebrity Apprentice, Trump would regularly disrespect the actress and would even treat her as if she were mentally disabled.

Sometimes the insults would be behind her back; other times they would be right in front of her.

Due to extensive non-disclosure agreements signed by members involved with the production, every one of the sources asked to be quoted anonymously for fear of legal retribution.

“[Trump] would often equate that she was mentally retarded,” said one source, who described how kind Matlin and her interpreter Jack Jason were.

During the taping of the show, Trump would often scribble down notes while sitting at the table of “the boardroom”—the show’s primary set. A person familiar with the notes who helped clean up after tapings said that on one of the pieces of paper, Trump wrote: “Marlee, is she retarded??”

“He would write notes on his blotter, his papers in front of him, and he would scribble notes in it,” a source described. “It was usually just asinine things on them.”

During breaks, Trump would often remain mic’d up and engage in chit-chat with Donald Trump Jr. or other people in the boardroom for tapings.

“[Trump] would make fun of her voice. It actually sounded a lot like what he did [to] the New York Times guy,” another person who worked on The Apprentice for years told The Daily Beast, referring to when Trump mocked a disabled reporter last year. The source said this incident occurred outside the boardroom, during a break from filming. “Like, to make it seem like she was mentally not there? [It] sounded like he got a real kick out of it. It was really upsetting.”

Another Apprentice staffer, who worked on the show for roughly five years, described how Trump commenting on Matlin’s deafness and supposed mental deficiencies was a regular occurrence during the whole season. Occasionally, it would be directly to Matlin’s face.

“In the boardroom, he would talk to her like she was ‘special,’” the source said. “He took her deafness as a some kind of [mental] handicap.” The staffer recalls sitting in the control room during the shoot for one episode and being taken aback hearing Trump make an “insensitive” comment about Matlin’s deafness to the actress while she was seated across the boardroom table.

“She responded [to him], she stood up for herself,” the source said. (This exchange was not included in the final cut of the episode.)

“But people would just laugh this [stuff] off—it was just the culture of [the show],” the staff member said. “But now it’s a little more serious because it’s not a joke anymore!”

Through an intermediary, Matlin declined to comment on this story.

“He would kind of do these mock voices,” a source said, who witnessed and heard one incident. “[Matlin] was a popular person on the show. I think he would take the low road and mock her disability.”

The Trump campaign did not respond to a request for comment on this story.

A day after the story was published, Matlin responded in a statement posted to Twitter.

"Recent media reports have circulated that Donald Trump allegedly referred to me as 'retarded.' The term is abhorrent and should never ben used. The fact that we are talking about this during a very important moment in American history has upset me deeply.

"I am Deaf. There are milions of Deaf and hard of hearing people like me, in the United States and around the world who face discrimination and misunderstanding on like this on a daily basis. It is unacceptable.

"So, what's the response? It's not about insults or taking each other down. As a person who is Deaf, as a woman, as a mom, as a wife, as an actor, I have a voice. And I'm using that voice to make myself heard...and vote."

This revelation comes on the heels of a rash of sexual-harassment and -assault accusations against Trump, as well as other allegations from a former Apprentice contestant, Richard Hatch, who claimed Trump also made lewd remarks to Matlin during taping.

“Watching him in the boardroom making sexual comments to Marlee Matlin, to all of the women on The Apprentice, it was obvious that that’s just a part of who he is,” Hatch told People magazine this week. “It was obvious and it was grotesque. It was blatant and it was frequent. He did it with Lisa Rinna; he did it with Marlee Matlin. He did it with whomever happened to be there at the time… He did it in front of Ivanka [Trump, his daughter]. That was not just uncomfortable for me. It was weird.”

“He doesn’t engage with women normally,” Hatch later told ET. “I think he thinks he’s complimenting people, when he’s practically drooling… My guess would be that he would describe it as flirting.”

Long before she appeared on Celebrity Apprentice, Matlin snagged the honor of becoming the first deaf actor or actress to win an acting Academy Award for her role in 1986’s Children of a Lesser God. She has appeared on various TV series including in a recurring role on Aaron Sorkin’s The West Wing. In 2011, she, alongside Snoop Dogg and Larry King, participated in the 2011 Comedy Central roast of Trump. (Matlin made a number of penis-related jokes at Trump’s expense during that broadcast.)

Late last year, Matlin told the New York Post about her relationship with the real-estate mogul and reality-TV star. “He treated me with respect and humor and was always looking after me,” she told the tabloid. When asked at the time if she was ready for a President Trump, she deflected, saying that “anyone can run for president!”

In January, Matlin tweeted: “I’m for my friend @HillaryClinton. If you’re with her, let her know.”

Editor’s note: This story was updated with Matlin’s statement on Friday, Oct. 14 at 2:34 p.m. ET.