A father has told the royal commission into child sexual abuse that his family felt completely let down by a Sydney music school, when he discovered that a teacher who had sexually abused their son was still being allowed to teach there.

The father, identified at the Royal Commission into Institutional Responses to Child Sexual Abuse as CAD, said his son was a talented music student when he started lessons with piano teacher Victor Makarov.

But unbeknown to the family, the boy was sexually abused by Makarov, who was employed at the Australian Institute of Music (AIM).

Makarov, who is serving a 12-year sentence after being convicted of multiple child sex offences in 2005, continued to teach at the school, even after sexual abuse charges were laid against him.

The commission, which is examining child sexual abuse at performing arts centres, heard that after Makarov was arrested and charged, the family was horrified to discover he was still giving lessons at the school.

"My wife and I found it unconscionable that Makarov continued to teach," CAD said.

The commission heard that the AIM asked no questions when CAD asked for a refund of the money he paid for his son's lessons.

"To allow an alleged predator to continue to teach or to remain around victims or other persons who may be placed at risk is completely incomprehensible to me," CAD told the hearing.

The commission heard that CAD was shocked to hear about the abuse, which began when the boy was 13 years old.

"Makarov had masturbated him, shown him pornographic CDs and sodomised him," CAD said.

"I was devastated. I had never experienced such emotional stress.

"My wife and I felt so betrayed. We were totally distressed, shocked, and confused."

Boy told sexual abuse would improve his music

His son, who is known as CAA, told the hearing he idolised Makarov and saw his abuse as part of what it took to become a concert pianist.

CAA said Makarov made him feel special and would abuse him while his father was waiting in the car outside.

"When he said that the music was all about sex, I believed him, because I respected him as a teacher, and because as far as my playing was concerned, he had achieved fantastic results," CAA said.

The front of the Australian Institute of Music school as it looks today. ( ABC News: Luke Rosen )

CAA, who is now 27, called for surveillance cameras to be installed in music rooms and for doors to the classrooms have large windows.

"There should be no blind spots in rooms which cannot be seen from the door," he said.

He also called on parents to be more active in supervising music lessons and not become complacent about the risks.

"Risk plays a major part in a paedophile's motivations," he said.

"Every time they beat the odds they get bolder."

He said it was not unusual in the performing arts for teachers like Makarov to be employed from overseas without any background checks.

"After Makarov was charged with criminal offences, my family found out from the Ukrainian students that before Makarov moved to Australia, it had been well-known within the music community in Ukraine that Makarov used to sexually abuse children," he said.

Protection of children 'not paramount concern of former director'

Raffaele Marcellino, who was the principal of AIM when the abuse came to light, told the hearing the school did not have adequate policies and procedures in place to deal with it at the time.

When asked why Makarov was not suspended when the allegations were raised he said the then director Peter Calvo, who died in 2011, thought that Makarov should be given the presumption of innocence.

The Australian Institute of Music building where some of the abuse perpetrated by Makarov occurred. ( ABC News: Luke Rosen )

Counsel assisting David Lloyd asked him: "Did he express to you whether he had the view that the protection of the children at AIM was paramount?"

Dr Marcellino replied: "No, that wasn't a primary concern of his".

In February 2004, AIM became aware of allegations against Makarov by two other students who had taken out AVOs against him.

The following month, the school suspended one of the students making the allegations while Makarov continued teaching.

Mr Lloyd said Dr Marcellino had previously told the hearing Makarov was a drawcard for students.

Mr Lloyd asked Dr Marcellino whether in allowing Makarov to continue teaching AIM had placed its financial interests and reputation above the welfare and well-being of the boys who made the complaints and the other students.

Dr Marcellino said it was not a financial decision.

In July 2004, Makarov said he wanted to go on extended leave until the completion of his criminal trial, but the school soon became aware that Makarov was continuing to see students at his home.