Heather Unruh, formerly of Boston's ABC affiliate WCVB, said in a news conference earlier today that the Oscar-winning actor brought her son "drink after drink" and then groped his genitals at a restaurant bar in Nantucket, Massachusetts, in July 2016.
A rep for the 58-year-old actor did not respond immediately to ABC News' request for comment.
"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," an emotional Unruh told reporters.
The former anchor said her son was not of legal age to drink, though he told Spacey that he was, and she says nor did he give the actor consent for what happened afterward.
Unruh said her son tried to shift his body to remove Spacey's hand but was only momentarily successful. "My son panicked. He froze," she said.
She said the violation continued with Spacey insisting that her son join him at a private party.
When Spacey left to use the restroom, a concerned bystander, a woman, asked Unruh's son if he was OK, Unruh said.
"Obviously, she had seen something and knew that he was not. She told him to run," the former anchor said. "And he did. He ran as fast as he could all the way to his grandmother’s house."
Unruh appealed to the woman to come forward.
She also had a message for the actor: "To Kevin Spacey I want to say this: Shame on you for what you did to my son. And shame on you for using your apology to Anthony Rapp to come out as a gay man. That was an appalling attempt to deflect attention from what you really are: a sexual predator. Your actions are criminal."
Unruh said her son did not go to police at the time "largely because of embarrassment and fear," but she said he filed a police report last week and provided evidence to Nantucket police.
Tara Miltimore, assistant district attorney and spokeswoman for the Cape and Islands District Attorney's Office, confirmed to ABC News that "an individual has provided information to the Nantucket Police regarding an allegation of an indecent assault and battery."
She added, "The individual is represented by an attorney. We are waiting to hear from his attorney."
In a statement to ABC News, Unruh said, "My son was in a place he felt very comfortable and safe. He worked at the Club Car as a busboy and had just finished his shift when Kevin Spacey came in."
Spacey's publicist has not responded to ABC News' requests for comment, though People magazine reported last week that a representative for the actor said that Spacey "is taking the time necessary to seek evaluation and treatment."
Bryan Freedman, a lawyer representing Spacey, told BuzzFeed, which published a story about Harry Dreyfuss' allegations, "Let me be clear, Mr. Spacey absolutely denies the allegations."
Spacey tweeted an apology to Rapp, in which he also came out as a gay man -- drawing widespread criticism for his coming out under those circumstances.