A mentally impaired Aboriginal woman who has been held in jail without trial or conviction for 21 months will be released next week to be closer to her family.

Rosie Fulton, 24, will be transferred from Kalgoorlie Prison in Western Australia to Alice Springs, where she will live in a house managed by staff from the Department of Health.

About 120,000 Australians signed a petition to have Ms Fulton freed after her story was broadcast on the ABC's Lateline program in March.

"I'm delighted that she's finally going to be out of jail after 21 months, and of course she is also ecstatic about the idea of coming back to Alice Springs and being able to contact her siblings. It's a really good outcome," Ms Fulton's legal guardian Ian McKinlay said.

In 2012, Ms Fulton was arrested after crashing a stolen car. A magistrate declared her unfit to stand trial and sent her to jail because there was no alternative accommodation available in Western Australia.

A psychiatric report found she had foetal alcohol syndrome (FAS) and had the mental age of a young child.

Mr McKinlay says Ms Fulton will be living in a suburban house with a community-based support model and will be provided with around-the-clock support.

Aboriginal leaders warn of more FAS cases in courts

Aboriginal leaders have welcomed Ms Fulton's release but warn more Indigenous children with FAS may soon come into contact with courts and prisons.

"We are going to see a wave of kids come through suffering from FASD (foetal alcohol spectrum disorder) and have this brain injury," Aboriginal and Torres Strait Islander Social Justice Commissioner Mick Gooda said.

"It affects them in a way that they can't communicate and learn the way the rest of us learn and they are just wired differently to us."

Mr Gooda said good work was being done in some Indigenous communities throughout Australia to deal with foetal alcohol syndrome and teach women not to drink during pregnancy.

However, he said that Ms Fulton may be the first of many cases which the police and courts have to deal with.

"We've got to start training our professionals - like the police, like the teachers and people in the health field. These are the kids that need to be dealt with differently," he said.

Call for audit of prisoners held with no conviction

There is no official record of the total number of mentally impaired prisoners held in Australian jails who have been deemed not fit to plead due to different state and territory prison systems.

Aboriginal Disability Justice Campaign spokesman Patrick McGee said up to 30 people with "some kind of cognitive impairment" would be detained in prisons without conviction per year.

Prison authorities in Western Australia said there were nine mentally impaired prisoners being held in their jails without conviction.

The Northern Territory Department of Health said 10 prisoners were being held without conviction.

Three are living in the Alice Springs secure care facility which was purpose built for the mentally impaired, while two other prisoners are undergoing a transition program to live in the Alice Springs centre.

The Aboriginal Disability Justice Campaign does not know how many prisoners in Queensland and other states are held without conviction.

La Trobe University professor Patrick Keyzer said the Federal Government needed to conduct a national audit of prison systems and fund facilities for impaired people to live outside of jail.

"The Federal Government really needs to take this issue seriously and sit down with the states and territories and develop a lasting solution," he said.

"It's outrageous that in a country like Australia, Aboriginal people are in prison when they have not been found guilty of a crime.

"Those people should not be in prison - they should be in a secure setting if that is necessary. Otherwise they should be supported in the community."

Professor Keyzer said in many cases people who were considered by the courts to be unfit to plead end up spending a long time in jail.

"They are staying in prison for a lot longer than they would have if they had actually been found guilty of the crime and sentenced," he said.