Stephen Neil White: Serial rapist who tried to murder a five-year-old girl by smashing her head with a rock is set to walk free from prison with $800,000 in NDIS support

A violent rapist who sexually assaulted and attempted to murder a five-year-old girl will be released from prison with $800,000 in NDIS support after more than two decades behind bars.

Stephen Neil White, 58, smashed a rock into the child's skull, tried to strangle her and raped her after abducting the girl from a tent in the West Australian town of Kununurra in 2001.

He was sentenced to 13 years' imprisonment with eligibility for parole, which was later increased to 17 years on appeal, with an additional 16 months for assaulting a woman in the tent.

White has been held in custody since completing his sentence under the Dangerous Sexual Offenders Act but that is set to end next month after the Supreme Court on Monday rescinded his continuing detention.

Smith is set to be placed on a community supervision order for three years, with $807,189 worth of NDIS support for one year, which includes all-male around-the-clock care.

The order comes with more than 60 conditions, including a curfew, a ban on drinking and viewing pornography, and no interaction with children, women and social media unless authorised.

The court found White had a significant cognitive impairment and chronic mental health issues, and there was "very clear medical evidence" he was at a high risk of serious sexual offending unless restricted.

"The respondent's re-offending would be both predatory and opportunistic towards predominantly vulnerable females of various ages, and would not involve much planning or grooming," Justice Michael Lundberg wrote in his judgement.

White's long criminal career started when he indecently assaulted a girl under 16 in 1983.

A year later he raped a 73-year-old woman in her home in South Australia and attempted to rape another woman while on bail.

He was sentenced to 12 years' imprisonment, with parole eligibility after eight years.

White, who has an acquired brain injury and an IQ of 62, has spent less than 25 per cent of his adult life in the community.

He also has a history of intravenous amphetamine, heroin and marijuana use and has been diagnosed with schizophrenia and antisocial personality disorders.

A psychiatrist concluded White was highly institutionalised and did not have the ability to engage in meaningful relationships and was highly impulsive due to his frontal lobe dysfunction.

His current mental state was determined to be stable and improved with the use of medication but this was at risk once he was released from prison.