A man accused of raping a fellow resident at a disability group home also sexually assaulted two other people on multiple occasions, the Victorian Ombudsman has found.
Disability services provider Autism Plus and the Department of Health and Human Services put clients at risk by failing to move the man despite repeated warnings, a report published by the ombudsman concluded.
Concerns were raised about "Edward", who cannot be identified, in October 2014, but he was not moved until he allegedly raped another resident six months later, Ombudsman Deborah Glass said.
"Edward also detailed that he had possibly sexually assaulted at least five other clients in Autism Plus group homes and day programs in the preceding years," the report, released on Monday, said.
"These other disclosures included sexual penetration of at least two other clients on multiple occasions."
The family of a resident raised concerns in October 2014 with Autism Plus, who then took the concerns to the department, but both sides disagree on what happened from there, Ms Glass said.
"(It was) striking for the fact that no one agency was prepared to take responsibility, nor were records kept of key decisions and the authority relied upon for making them," Ms Glass said.
Ms Glass said Autism Plus reluctantly kept Edward in the home, but they were also motivated by the fear of losing government funding.
Six days after Autism Plus cut overnight staff numbers for financial reasons, Edward raped the resident whose family had originally raised concerns.
"This case is especially shocking," Ms Glass said.
"Not only because of the enduring impact of the trauma associated with sexual assault, or the acute vulnerability of those involved, but that this could still happen today despite the supports available to people with a disability."
The Ombudsman criticised DHHS for failing to move Edward, and child protection authorities for failing to visit him for three years despite his involvement in more than 30 physical and sexual assaults and property damage incidents.
Autism Plus responded to the Ombudsman's report to say the "system" had failed Edward and his victims, and the report relied too much on DHHS' version of events.
The company said the report portrayed a picture of Autism Plus "as dimly as possible" without any allowance for the difficult environment in which it operates.