"I am now unemployed, under-educated and still looking for a life path," he wrote in a submission to the Royal Commission into Institutional Responses to Child Sexual Abuse on May 23.

He had been prompted to tell his story for the first time in more than two decades by the news the commission was to hold a public hearing in Canberra starting on Tuesday, June 10.

While specific details of his allegations cannot be published as they have yet to be tested in a court of law, Mr Hopkinson names a brother, whose name has not come up in previous investigations and court actions, as an alleged sexual predator.

Mr Hopkinson says while he was never sexually abused himself, he did become aware other children were being molested, and that in his final year at the college in the mid-1990s, he confronted staff over that abuse.

"I was victimised by this individual [the alleged sexual predator] for three years [from year 4] and when I progressed into the senior school, the victimisation continued through different brothers."

Mr Hopkinson, who admits to having issues with authority and says he was a chronic truant in his last months at the college, spent his whole school career in the Catholic education system.

"We lived in Florey; mum was a nurse and dad was a scientist," he said. "I went to Sacred Heart in Pearce until year 2 and then St John the Apostle for year 2 and 3."

He has told the commission he was a student at Marist College for the next seven years.

"I left the school in Year 11 and never completed any form of official higher education or Year 12 certificate," Mr Hopkinson’s submission states. "These brothers ruined my life; I am finally keeping my promise of telling the authorities and the media about Marist College Canberra."

Asked why it has taken so long for him to come forward, Mr Hopkinson gave a number of reasons, all of which are interlinked.

"I have talked about this to counsellors and to close friends in the past," he said. “But I just thought nobody really cared. Also, I had seen the way the church responded to people who did come forward and that discouraged me [from telling my story].

"I believe one of the reasons the church fought so hard [to marginalise people who reported abuse] was to discourage others."

This was compounded by the fact he had lost a decade or more in the immediate aftermath of his experiences at Marist College.

"I spent about 10 years not paying attention to the world," he said. "I was either online gaming or web surfing. I just stayed out of the loop."

Mr Hopkinson said the commission had come as a breath of fresh air and should be kept running until there was no more evidence for it to hear, even though it is only funded until the end of next year.

"You can see that the commission is different," he said. "People are being believed; bishops have apologised; you never saw that before. It obviously has some weight."