The 31-year-old man who last week sensationally named Hollywood heavyweight producer Bryan Singer in a child sex lawsuit has filed three more civil lawsuits against powerful Hollywood figures.

The three named today are former 20th Century Fox television boss Garth Ancier, former Disney television boss David Neuman and Broadway producer and Universal and Six Flags theme park designer Gary Goddard.

"Somebody has to stand up to these people," the alleged victim, Michael Egan, told a packed press conference in Los Angeles. "You can't change the stigma that exists in this world against childhood sexual abuse unless someone talks about it."

Egan spoke out last week, accusing Singer, a prominent Hollywood producer, of a series of sexual assaults that occurred when Egan was aged 15 through to 17.

Egan's lawyer Jeff Herman said the assaults took place at a private LA estate which played host to parties attended by high-profile Hollywood figures and "underaged boys, including Mike [Egan]".

At those parties the young men were "given drugs, they were given alcohol, sometimes they were threatened, sometimes they were given gifts and promised roles in movies; what we call being groomed," Herman said on Monday, US time.

Herman said the subjects of the four lawsuits are part of a "ring" of powerful Hollywood figures who were "participants" in the parties, and had sexually assaulted Egan.

Herman said there were allegations which touched on a number of other figures, but the four names so far were the only four connected to parties in Hawaii as well as Los Angeles. The connection to Hawaii is significant, as it is the jurisdiction in which the lawsuits have been filed.

No criminal charges have been laid against any of the four named.

Egan's mother, Bonnie Mound, attended the press conference to support her son and delivered an explosive and emotional criticism of the difficulties she faced for the past 14 years in trying to make people, including law enforcement agencies, act on her son's claim.

She told the press conference that she had first discovered her son was a victim of sexual abuse when he was 17 years old, but that her subsequent pleas for help — to the LAPD, FBI and various media outlets including 60 Minutes and the Oprah Winfrey Show — were ignored.

Despite interviews with the police and federal agencies, nothing was done, she said. A single journalist attempted to write a story for a magazine, she said, but the story was abandoned after pressure from the Hollywood establishment.

"There is talk that Mike is here for his 15 minutes of fame; do you call this fame?" Mound said, breaking down in tears. "This isn't fame. What part of this is fame?

"Sitting here ... do you think we like it? It's not about money, it's about disarming these paedophiles who use their wealth and power to escape justice," she said.

Herman said the lawsuit was simply about "grown men sexually abusing children".

Asked by a reporter why she had not noticed her son was being sexually abused over a period of two years, Egan's mother responded with a mixture of rage and raw emotion.

"Do you have any teenagers? Do they tell you everything?" she pressed the reporter.

"Do they tell you when these paedophiles have knives at their throats, stick guns in their mouths, have a bodyguard stand above their head and say they're going to snap heir neck, put them underwater till they about drown, lock them in a [gun] safe till they can't breathe?

"Then tell me, would your teenager tell you or would they be petrified? Would they be scared out of their mind when they have threatened death to them and our family? Then you think about it. I hope you never have to go through what we've gone through. I hope not."

Singer's lawyer, Martin Singer — no relation — responded to his client's lawsuit last week with a statement in which he said the claims were "completely fabricated".

He also said he would bring a claim of malicious prosecution against Egan and Herman.

On Monday, Herman accused Singer's camp of intimidation.

"I am not going to be bullied. I am not intimidated by those kinds of statements," Herman told the press conference. "And I will continue to file cases on behalf of victims of sex abuse.

"To all the victims who hear these threats and feel its not safe for them [to come forward], I want them to know it's safe for them, it's safe to come forward," Herman said.

Herman said the four lawsuits were filed after more than six months of investigation.

Herman is one of the most respected advocates for survivors of rape, sexual abuse and sexual exploitation in the US, notably representing hundreds of victims of clergy sexual abuse in the Roman Catholic church.

The case has triggered a mixed reaction in Hollywood, generating coverage from many media outlets but cautious coverage from others, particular media outlets which have either have connections to or depend on the Hollywood studio infrastructure to operate.

Herman said the case was "a watershed moment for Hollywood".

"We're going to look back on these cases and see this opened up a number of victims feeling safe about coming forward," he said.

Herman said he had been contacted by dozens of victims who have alleged abuse by different perpetrators, including studio executives, managers, directors and producers.

"This is something I anticipate will expand. I will continue, as appropriate, to file cases and expose the predators."