In July 2016, Unruh said her then 18-year-old son was at The Club Car, where the "House of Cards" actor was among the late-night crowd in the dimly lit restaurant.
Her son was mesmerized by Spacey, 58, Unruh said, and told him he was old enough to drink.
What happened next, Unruh alleged, was criminal. She said Spacey purchased alcohol for her son until he was drunk and then stuck his hand inside the man's pants and grabbed his genitals.
"The victim, my son, was a star-struck, straight, 18-year-old young man who had no idea that the famous actor was an alleged sexual predator or that he was about to become his next victim," said Unruh, who was accompanied by attorney Mitchell Garabedian and her daughter Kyla. "This was a criminal act."
Unruh's allegations are the latest to be lodged against Spacey since last month, when actor Anthony Rapp said the movie and television star had made an unwanted sexual advance toward him in the 1980s. Spacey was 26 at the time and Rapp was 14.
Unruh said her son, now a 19-year-old college sophomore, reported the incident to Nantucket police last week and provided evidence to investigators. A police spokesman declined to comment, saying reports of sexual assault are confidential under state law.
Cape and Islands District Attorney Michael O'Keefe said prosecutors have contacted the lawyer for Unruh's son but haven't heard back.
"We don't do things by press conference," O'Keefe said.
Spacey's attorney didn't respond to requests for comment. In the wake of Rapp's accusation, Spacey said through a publicist that he was seeking unspecified treatment. He also revealed he was gay, a disclosure that was irrelevant to Rapp's allegation and drew widespread criticism.
Netflix has shut down production of "House of Cards," which had been filming its sixth and final season. On Wednesday, it was revealed by the Associated Press that Spacey would be cut from Ridley Scott's finished film ''All the Money in the World'' and replaced by Christopher Plummer just over one month before it's supposed to hit theaters. All of Spacey scenes will be reshot.
During the news conference at a Boston hotel, Unruh occasionally fought back tears as she described the alleged attack and lauded women who have publicly accused movie mogul Harvey Weinstein of sexual assault for giving her son the courage to tell his story.
During the encounter, Unruh said, her son tried to shift his body away from Spacey but was "only momentarily successful." The actor urged her son to accompany him to an after-hours party to drink more, she said.
Unruh said her son fled the restaurant when Spacey excused himself to use the bathroom and a woman urged the youth to run. He sprinted to his grandmother's house and told his sister what happened, Unruh said. The siblings then called Unruh, who traveled to Nantucket in the morning, she said.
"To Kevin Spacey I want to say this: Shame on you for what you did to my son," she said. "Nothing could have prepared my son for how that sexual assault would make him feel as a man. It harmed him and it cannot be undone."
She said Spacey should go to prison and asked the woman who went to her son's aid to come forward. "I know that she had the presence of mind and was disturbed enough by what she had seen to approach a young man who's almost 6 feet tall and ask him if he's OK," Unruh said.
Her son asked Unruh to speak publicly about the encounter, she said. He didn't go to authorities sooner, she said, because of embarrassment and fear. Soon after the alleged attack, however, Unruh said she discussed it with Nantucket's sheriff, who urged him to file a complaint.
She initially accused Spacey of wrongdoing on Oct. 13, writing in a tweet that she was a fan of the actor "until he assaulted a loved one." She did not identify the relative in the tweet. During her news conference, Unruh also alleged Spacey had targeted another man during a visit to the island.
Garabedian, who rose to prominence representing victims of clergy sex abuse, is representing Unruh's son.
In a statement, Club Car's director of operations Ty Costa said the staff was saddened to read Unruh's account. The current ownership purchased the business after the alleged assault occurred, Costa said.
The restaurant's former owner, Joseph Pantorno, didn't respond to requests for comment. A police official said records going back to 2011 show the restaurant hasn't been cited for serving alcohol to minors.
Legal specialists said Unruh's son could face scrutiny if Spacey is prosecuted. "I think he can definitely expect to have to explain the fact that he was drinking and underage," said Colby Bruno, senior legal counsel for the Boston-based Victim Rights Law Center, an advocacy group for sexual assault victims.
A defense lawyer would likely press Unruh's son on questions of consent, she said.
"He wasn't [a minor] at the time, so they're going to try to place as much blame on him as they possibly can for the encounter. And of course he isn't to blame, but that's what a defense attorney does," Bruno said.
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