Detective Superintendent Des Bray says while Smith could not drive, she was given a car so carers could drive her around and take her to appointments.
But he says someone had driven the car on other occasions and had racked up four speeding and red light camera fines worth more than $2000.
Bray says detectives want to talk to a man who was seen coming to her house and taking her car at one stage, returning it to the property just before her death.
They also want to hear from a man and a woman who visited her home in October and November 2018, during a period when carers were not engaged.
Bray says the investigation in relation to Smith’s death this year is becoming more troubling as more information emerges.
“As the days pass, there’s lots of things that have come out in this investigation that I wouldn’t have thought would ever happen,” he said.
“I just find it inconceivable that she could receive the treatment that she did or that she could be exploited in any way, shape or form.”
The 54-year-old, 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.
Before her death, she had been spending her days and sleeping at night in the same woven cane chair, with extremely poor personal hygiene.
As well as the police investigation into her treatment, the NDIS commissioner has appointed former Federal Court judge Alan Robertson to lead an independent inquiry.
Earlier this week, police said jewellery worth $35,000 was missing from Ms Smith’s home along with other items, including two fridges.
Bray said those items remained missing and detectives had still been unable to find any of the dead woman’s health records since 2015.
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