Knox Grammar School was advised to destroy documents relating to child sexual abuse while at the same time preparing an apology to victims, a royal commission has heard.

A series of emails tendered in evidence to the Royal Commission into Institutional Responses to Child Sexual Abuse revealed an unnamed solicitor had recommended the destruction of documents in 2009, following the arrests of five teachers who abused children at the Uniting Church school.

One email with the subject heading: "apology drafts", implicates former moderator of the Uniting Church in Australia, Synod of NSW and the ACT, James Mein in the act.

"The solicitor who drafted this is one who has been advising the school to destroy documents, with Jim's assistance," Uniting Church manager of insurance and property services Dwane Freehely wrote.

Rob Wannan, a high-profile solicitor and chairman of the Knox Grammar School Council from 2007-13, said the "Jim" in the email was likely to be Mr Mein but denied that he was the person who ordered the destruction of the documents.

James Mein has been called to give evidence to the commission.

The current headmaster of the Wahroonga school John Weeks told the commission he first heard rumours about the inappropriate behaviour of one teacher, Adrian John Nisbett, in the mid-1990s.

Nisbett started working at the school in 1971 and the commission has heard he abused a number of students over a 30-year period.

Mr Weeks told the commission he believed former head master Ian Paterson was covering for Nisbett.

"Adrian Nisbett was considered to be a protected species at Knox Grammar School . . . protected by the headmaster," he said.

When Mr Weeks became head master in 2004 he told the commission he wanted to sack Nisbett, then the head of student welfare, on the spot.

"There were red flags everywhere from my point of view . . . I wanted him gone," he said.

Mr Weeks told the commission he hired an internal investigator to prepare a report on Nisbett. The investigator's report, tendered in evidence, found that Nisbett had said to boys: "Do you like men? Do you have feelings for men? Are you interested in a homosexual lifestyle?" as well as groping one boy in his photographic dark room.

A copy of the report was given to the NSW Ombudsman which failed to notify the police or advise the school to report the incidents to the police.

Mr Weeks told the commission the Association of Independent Schools advised him there were not sufficient grounds to sack Nisbett.

Instead, Nisbett was allowed to "resign" in September 2004 to take up a position with the Cheetah Conservation Fund in Namibia.

Nisbett was arrested in 2009 and convicted of a number of sex offences involving three students. The commission heard he is in South Africa and is unable to be summonsed.

A warrant for the arrest of another former teacher, Christopher Fotis, remains in place.

The hearing before Justice Jennifer Coate continues.

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