A 48-year-old intellectually disabled man who has been declared a dangerous sex offender faces a "life sentence" because no government department will take responsibility for his difficult case, a Supreme Court judge has warned.

In a decision on Monday, Justice John McKechnie said he had no choice but to make an indefinite custody order for Stephen Michael Jonsson to ensure adequate community protection.

Jonsson has an overall IQ of 66 and has been a client of disability services agencies since he was three. He was physically abused by his father and had early behavioural problems. He was put in an institution at 10 and stayed there for 19 years.

Jonsson was sentenced to supervision orders in 2007 and 2008 for offences including two of indecent dealing with young girls. In February 2011 he was jailed for 14 months for lurking near a train station and detaining an eight-year-old girl in a men's toilet with intent to cause her detriment.

He was assessed in jail as suitable for sex offender treatment for people with intellectual disabilities but the course was cancelled.

His lawyer accepted he was a serious community danger with the options being community supervision or continuing detention. Evidence was given that if released, Jonsson would need 24-hour supervision at a cost of at least $250,000 a year.

Justice McKechnie said neither the Disability Services Commission nor Department of Corrective Services would fund the supervision. Only a non-government agency would make a proposal.

Corrective Services Commissioner Ian Johnson said he understood the supervision required for Jonsson would cost more than $1 million a year.

"If a person is of such a risk that they require full-time supervision, then the only place we can do this is in a prison," he said.

Disability Services Commission director-general Ron Chalmers said the agency would fund Jonsson's disability-related needs if he was released but could not provide "security-related services".

The West Australian

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