A woman who cared for disabled Adelaide woman Ann Marie Smith has been charged with manslaughter over her death.

Ms Smith, who suffered from cerebral palsy, died in hospital in April from septic shock, multiple organ failure, severe pressure sores and malnourishment while under the care of the National Disability Insurance Scheme.

Police launched their investigation soon after while the NDIS commissioner has appointed former Federal Court judge Alan Robertson to lead an independent inquiry.

They said Ms Smith, 54, had been spending her days and sleeping at night in the same woven cane chair with extremely poor personal hygiene and no nutritional food.

On Thursday detectives charged a 69-year-old woman with her manslaughter.

She is expected to appear in Adelaide Magistrates Court on Thursday or Friday.