The teenager who was allegedly assaulted by Hollywood actor Kevin Spacey filmed part of the attack on Snapchat, Massachusetts State Police said.

The 18-year-old son of former Boston news anchor Heather Unruh told police he sent a video of the actor groping him in a Nantucket bar to his girlfriend as proof of the alleged July 2016 assault, Page Six reported, citing a state police report filed with a criminal complaint in Nantucket District Court.

The video, which hasn’t been officially released, reportedly contained a recording of Spacey touching the front of the young man’s pants, according to state police documents reported by Mass Live.

Spacey, 59, was charged Monday with indecent assault and battery — over a year after Unruh first spoke publicly about her then-18-year-old son’s alleged assault. The report contains the first detailed description of Spacey’s alleged actions.

According to the report, the actor was introduced to Unruh’s son when the teen finished his busboy shift at the Club Car, a local restaurant. Unruh’s son told Spacey he was 23 years old and the House of Cards star then offered to buy him a drink.

“Things started to get a little fuzzy when [Unruh’s son] and Spacey went over to the piano,” Trooper Gerald F. Donovan wrote in the report. “[Unruh’s son] said he had at least four or five beers before Spacey said they should switch to whiskey adding, ‘Let’s get drunk.’ ”

According to Donovan, the teen told Spacey about his girlfriend of five months, yet Spacey told him “to stop texting her and began talking about the size of his penis”. While smoking outside, the actor also allegedly asked Unruh’s son to come back to the house where he was staying — but the teen refused.

When they went back inside, Spacey allegedly began rubbing the teen’s thigh while standing in a crowd of people around a piano and then allegedly unzipped the teen’s pants and touched him without consent.

“[Unruh’s son] didn’t know what to do. He didn’t want to get in trouble at work or get his work in trouble,” the trooper wrote in his report. The report also said that the teen told his girlfriend about what happened but she did not believe him so he Snapchatted the video. He then left the bar on the advice of a woman who reportedly saw that "he was in distress." He returned to work the next day and informed the owner of the bar about the incident, court documents said.

The filing stated that police had retrieved the footage and presented it to the young man, who confirmed that it contained him and Spacey. 

“[Unruh’s son] said the whole thing was embarrassing and has not had a ‘profound emotional effect’ on him. [He] told his friends about it and makes jokes about it because that is his way,” the report said.

The assault was first reported to Nantucket police on Oct. 31, 2016, but the investigation didn’t move forward until Nov. 22, 2017, when the accuser spoke with Massachusetts State Police.

The actor will be arraigned on charges of indecent assault and battery on January 7 at Nantucket District Court in Nantucket, Massachusetts. Earlier on November 16, 2017, The Old Vic theatre disclosed details regarding previous allegations of inappropriate behaviour made by 20 men against Spacey during his tenure there as artistic director from 2004 until 2015.