People shed tears at a Sydney hearing as they watched a young man with autism become agitated as he slowly typed about being abused at a NSW disability centre.

The royal commission into child sexual abuse showed videotaped evidence from the now 20-year-old on Tuesday during a hearing into how service providers The Disability Trust and Shoalhaven Interchange, both in south Sydney, handled allegations of abuse.

The man, known as CIE, uses a QWERTY keyboard to communicate.

His evidence named his abuser as Royce Comber, who in 2012 was a part-time worker with both providers.

The commission heard Comber declined to be interviewed by police during an investigation but denied the allegation to the Disability Trust.

CIE's video evidence taken by the royal commission over four hours followed testimony by his mother who said her son had moderate autism but scored highly on maths and English tests as well as in NAPLAN testing.

She said in March 2012, CIE had communicated to her that Disability Trust worker Royce Comber had "touched him on the willy" in the toilets.

In his video evidence to the commission CIE slowly typed on an iPad held by his mother that Comber had touched his penis and tried to suck him.

The mother known as CIF said a police Joint Investigation Response Team (JIRT) had interviewed CIE in 2012 but later told her the allegations against Royce Comber were "substantiated" but they could not proceed to prosecution because her son was not a reliable witness.

CIF, a teacher, was highly critical of the JIRT approach and called for reforms which would see a specialised team dealing with disabled children.

Margaret Bowen, CEO of the Disability Trust said Comber did not continue to work at the trust after the allegation.

The trust followed procedures including an internal investigation required by the Ombudsman after police finished their inquiry but Ms Bowen said she could find no corroborating evidence supporting the allegations and found it difficult to weigh the evidence.

"At the end of the day I did not know if it had occurred as said or occurred differently ... I found the process a big expectation because you want to do everything right, you want to be fair."

Some of the Ombudsman's and police language needed clarification especially when it came to terms like allegation "substantiated", she said.

Gail Furness SC counsel advising said the commission had no problem with the way the Disability Trust handled the complaint and there would be no finding against it.

Ms Bowen is the second witness at this hearing to express concern at complex procedural requirements around internal investigations of child sexual abuse.

Earlier on Tuesday the commission heard from the head of Mater Dei school who said an agency overseen by the ombudsman was needed to help small organisations investigate child sex abuse especially when it came to disabled children.

The hearing before Justice Jennifer Coate resumes on Wednesday.

from http://www.9news.com.au/national/2016/0…

see also http://www.theage.com.au/national/sex-a…;