An investigation of child sexual assault was made more difficult by a "love letter" written by the alleged victim to his abuser, a hearing has been told.
A love letter written by a man claiming to be a victim of child sexual abuse to his alleged abuser made it difficult to later verify if the crime had taken place, a royal commission has been told.
John Bednall was principal at The Hutchins School in Hobart for nine years from 1987.
During his leadership the school received a complaint from a man, known only as AOA for legal reasons, claiming to have been sexually abused while a student in 1964 by then headmaster, David Ralph Lawrence.
AOA sought acknowledgment that the abuse occurred and an apology from the school.
Charged by the Hutchins board with examining the veracity of AOA's claim, Dr Bednall was unable to reach a conclusion in what he titled a complex affair.
He denies he was trying to cover up the report to protect the school's reputation or its exposure to litigation, and instead says there was a lack of information allowing him to make a finding.
Adding to his difficulty was a letter, written by a 21-year-old AOA - six years after the alleged abuse - to Mr Lawrence.
The letter was intercepted by a school secretary and pre-empted Mr Lawrence's resignation.
During his inquiries, Dr Bednall was told of the sexually explicit correspondence which was described to him as a "love letter".
"I'm not qualified ... to understand why AOA would have maintained contact into adulthood with a man whom he claimed had abused him as a boy," Dr Bednall told the commission on Friday.
But he said the letter made him wonder "what was actually happening in this young man's mind?".
Counsel assisting the commission, Angus Stewart SC, said the Hutchins board had failed a moral test by not apologising to AOA.
"I suggest that integrity, compassion and dignity demand from the board in the face of the information that it had, that it apologise to AOA," Mr Stewart said.
He further accused Dr Bednall of being motivated to protect the reputation of the school during his investigation.
But Dr Bednall rejected the assertion.
"I never at any stage said to the board we should try to cover this up," he said.
"I did the best that I could and I tried to be absolutely fair to AOA."
More than two decades after it was first sought, Hutchins apologised to AOA in October.
The royal commission is looking at how the school and the Anglican church responded to reports of sexual assault at Hutchins which involve allegations against eight members of staff including Mr Lawrence.
The hearing continues on Monday before commissioner Andrew Murray.