Sizemore was told to leave the set of the crime thriller Born Killers, which was eventually released in 2005 under the name Piggy Banks, after the child actress reported the incident to her mother.
There is a watershed moment occurring in Hollywood, with many men in the industry being accused of sexual assault, harassment, and rape in recent weeks.
USA TODAY reached out to Sizemore's representatives but has received no response. His management firm Untitled and talent agency CAA dropped him shortly after the allegations.
According to claims the girl was sat on Sizemore's lap for the shoot when the actor is alleged to have fondled the girl. The actor had a reputation on the set for being hard, and was often drunk or high during filming.
She said: "I'm not speaking out for myself, I'm speaking out for the girl who is a woman now".
Cast member Robyn Adamson, who portrayed Sizemore's wife in the movie, claimed she noticed the girl suddenly appeared alarmed during the time of the alleged assault. She soon reintegrated and kept going, although she had trouble taking direction. He has publicly battled drug abuse since he was a teen, and was charged with with possession of methamphetamine in 2007.More news: Conor McGregor: UFC champion apologises for Dublin behaviour but blames referee
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The next day, casting director Catrine McGregor said she got a call from the young girl's agent, informing her that the girl had told her mother she had been inappropriately touched.
The young actress, now 26, was unidentified at her request; she told THR she didn't want to talk about the matter except to say that she's recently hired a lawyer to explore legal action against the actor as well as her parents.
A former production assistant, Roi Maufus, told The Hollywood Reporter: "The little girl said what she said and we all thought, "That fucking sleazebag.' There was never any doubt".
Cassidy Lunnen, the production manager recalled, "the girl was so young it was unclear to her and (later) her parents what had actually taken place and if it was intentional or not".
"We had a fiduciary responsibility to complete the film so we chose to go about business as usual - lacking the evidence of what happened that day", producer Gus Spoliansky said. "He was this guy who was already known for making inappropriate comments, being drunk, being high". "We're talking about consistent behavior, just being 'Tom Sizemore" on set every day.
They spoke with Sizemore about the incident in question, and he responded, "I've done a lot of very bad things, and I'd never do anything with kids". While they did speak to the police about the alleged incident, no charges were filed.