A Geelong Grammar School nurse has paid tearful tribute to boys who committed suicide after suffering at the hands of a serial molester who abused more than 40 boys at the elite school.

Two witnesses have told the Royal Commission into Institutional Responses to Child Sexual Abuse the school did not report to police the sexual abuse of one student, who was then expelled when he tried to have his complaint investigated.

It has also been told numerous warnings were given about the strange behaviour of Philippe Trutmann, who worked as a boarding house assistant in the 1980s and 1990s.

In 2005, Mr Trutmann was convicted of sexually abusing at least 40 male students between 1985 and 1995, and sentenced to 6½ years' jail.

Catherine Parsons, who has worked as a matron and nurse at Geelong Grammar on and off since the 1980s, told the commission on Thursday that several boys had died from suicide and drug overdoses after being abused by Trutmann.

"My absolute wish is that the victims who have been so terribly affected, their families who have suffered enormously, those beautiful children who have died, the families who mourn and those boys who continue to suffer with drug and alcohol problems, homelessness and a living hell, that we honour them by insisting on a culture within our boarding houses that is caring, open and transparent ... and that we remember them always," she said.

She wept as she told of one boy, who died in 1994 from a heroin overdose. She suspected the boy had been abused by Trutmann, because his behaviour had spun out of control the previous year after he stayed at the Trutmann family home near Ballarat, when he was 15.

Mrs Parsons said she had repeatedly told the master and deputy master of the Highton boarding house that Trutmann "continually flouted" school rules that adults should not be left alone with children.

"It was well known", she said, that Trutmann would give boys back rubs at night with the lights out, and sometimes with the boys' doors closed.

In 1989, she tried to help a 14-year-old boy, who can be identified only by the pseudonym BIW, who had been sexually abused by Trutmann.

BIW told the commission he was abused just two weeks after starting at the school, and was expelled after he reported the abuse.

The man said that after he was expelled, the school billed his mother $2500 in unpaid fees, and threatened her with legal action if she did not pay. It was only when the single mother engaged a lawyer to fight the matter that the school dropped its threats.

BIW told the commission he had woken one night to find a man's hand beneath his bedclothes, masturbating his genitals.

Afterwards, he said: "I stayed laying in my bed extremely scared and not believing what had just happened to me. I couldn't sleep or do anything. I was scared he could come back at any time and do this again."

The next morning the boy told his mother and Mrs Parsons what had happened to him.

Within hours, he said, he was called to a meeting with Highton master Robert Bugg, deputy master Paul Claridge, and Mrs Parson, where the men grilled him about his version of events.

"I felt they didn't believe me," he said. "It was as though I had broken into these people's homes and destroyed everything they loved; it was just surreal."

The next day, the school expelled him, he said.

"I was tormented for years knowing that I had been expelled from school for reporting the truth.

"My abuse was never reported to police. I felt terrible guilt that I had left other children at the hands of a sex offender. I knew that other children would be abused because no one would listen to me."

Trutmann was later convicted of sexually abusing BIW, and given a 12-month suspended sentence for the attack.

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