The sixth and final woman to accuse Harvey Weinstein of sexually attacking them took the witness stand at his rape trial on Wednesday, describing in harrowing detail how he allegedly groped her in a Los Angeles hotel bathroom in 2013.

The jury in the New York supreme court were once again subjected to a graphic and distressing account of an alleged forced sex act imposed on an aspiring young actor by the once-powerful movie producer.

Lauren Young, 30, a model from Pennsylvania, recounted how she had been invited by a female acquaintance to the Montage hotel in Beverly Hills on 19 February 2013.

She went in the hope of showing Weinstein a film script she was writing based on her life. The film producer appeared in the lobby of the hotel and they began talking about the reality TV show America’s Next Top Model which he suggested Young might be able to join.

They continued talking about the show as Weinstein asked Young and the other woman up to his hotel room, she told the jury. She was led into the suite – Weinstein in front of her, the acquaintance behind her – following the defendant through the living room, down a corridor and into the bathroom.

Suddenly, Young said, the encounter turned coercive. As she entered the bathroom she saw through a mirror that her acquaintance had closed the door behind her, shutting her and Weinstein in.

The movie producer, the witness alleged, went to the shower, turned it on and immediately started undressing.

“I stood there in shock. He was already naked at that point. He stepped in front of me when I went to approach the door with his naked body right in front of me. I felt so trapped.”

Young went on to claim that Weinstein pushed her back against the bathroom sink, unzipped and pulled down the white lace dress she was wearing, and began groping her breast as he masturbated. “I said ‘no, no, no’, the whole time; that I had a boyfriend; that I wasn’t interested. He’s carrying on with conversation, ‘This is what all actresses do, to make it’.”

The defendant continued to masturbate, Young said, until he ejaculated on a towel.

Young was asked by prosecutors to describe any memorable features of Weinstein’s anatomy. She said that his genitals were peculiar.

“It looked like it had been cut and sewn back on, not a normal-looking scar from circumcision. Something looked wrong. I didn’t really see balls in a sack.”

The film producer’s body parts have emerged as an evidentiary factor in the trial. One of the two main accusers in the case, who alleges she was raped by Weinstein in a New York hotel in 2013, told the jury that he appeared to be “intersex”.

“He does not have testicles and it appears he has a vagina,” the accuser said in testimony earlier this week.

On Tuesday prosecutors showed the jury official photographs of the movie mogul’s body. The images were handed to jurors to inspect without being visible to the public in the courtroom.

Young is one of three witnesses who have been included in the trial even though their allegations are not actively being prosecuted. They have been called to provide evidence of “prior bad acts”, a type of supporting testimony known as Molineux witnesses under New York law.

Weinstein, 67, has pleaded not guilty to five counts and faces a possible sentence of life imprisonment. Two of the counts are rape, relating to the woman who alleges she was violated in 2013, and one count is that he forced oral sex on the former production assistant Miriam Haley in 2006.

The two other counts are for predatory sexual assault – the idea that Weinstein displayed a pattern of behavior, or modus operandi, going back several years. These are the counts that carry the potential life sentence.

As a further complicating factor, Young is one of two women accusing the film producer of sex crimes in a case being prosecuted by the Los Angeles district attorney’s offices. Charges in that separate case, for which Weinstein faces up to 28 years in prison if convicted, were announced on 6 January – the same day as the New York trial began.

After Young gave her testimony, she was cross-examined by one of Weinstein’s defense lawyers, Damon Cheronis. In a dramatic move, he produced the white lace dress that the witness alleged she had been wearing at the time of the 2013 incident and had never worn since.

Cheronis pressed Young over how she had come to discover the dress only three days ago, she said in a box of clothes she had left behind in LA after a house move. The court heard in earlier legal argument that LA prosecutors intend to test the garment for DNA that may or may not tie it to Weinstein.