Transcript for A new accusation against Kevin Spacey
And we begin with that Boston mother, coming before the cameras today, a former TV an corp with a new claim of sexual assault by actor Kevin spacey. Fighting back tears, talking about what he allegedly did to her 18-year-old son. Heather Unruh detail what her son says happened, and the alleged witness who told her son to run. ABC's linsey Davis leading us off. Reporter: Tearful moments today, as a former Boston news anchor came before the cameras to talk about what her son says Kevin spacey did to him. First, I just want to let you know that I am here not as a journalist today, but as a mom. In July 2016, actor Kevin spacey sexually assaulted my son. The victim, my son, was a star-struck, straight 18-year-old young man. Reporter: Heather Unruh says her son told spacey he was of legal drinking age even though he was just 18. But whether he was over 21 or not, Kevin spacey had no right to sexually assault him. There was no consent. Kevin spacey bought him drink, after drink, after drink, and when my son was drunk, spacey made his move and sexually assaulted him. And I want to make it clear that this was a criminal act. Reporter: Unruh on what her son told her. Spacey stuck his hand inside my son's pants and grabbed his genitals. This was completely unexpected. And my son's efforts to shift his body to remove spacey's hand were only momentarily successful. The violation continued. My son panicked. He froze. Reporter: She says spacey insisted that her son go with him to a party. Then, the actor left to use the bathroom. A concerned woman quickly came to my very shaken son's side and asked if he was okay. She told him to run. And he did. He ran as fast as he could. All the way to his grandmother's house Reporter: She says he woke up his sister and together they called their mom. 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. Reporter: She says her son filed a police report last week and handed over evidence. Netflix had already severed ties with the "House of cards" actor after mounting harassment allegations. Unruh praised actor Anthony Rapp, who said spacey made a sexual advance toward him when he was just 14 years old. 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 away from what you really are -- a sexual predator. Your actions are criminal. And linsey Davis with us now. We heard Heather Unruh describe there a woman she says helped her son, telling him to run. That's the account offered by her son and they would like to try to find that woman? Reporter: She says her family is grateful to this woman. She said when she saw something she thought was wrong, she acted, and they would like to thank her in person. And this lady will likely be a witness, as well. Want to add that we did reach out to Kevin spacey for comment, with with regard to the latest allegations and we did not hear back. David? Linsey, thank you. We turn next here to the urgent manhunt under way right
This transcript has been automatically generated and may not be 100% accurate.