SA Police have raided the business which employed an Adelaide woman charged with the manslaughter of Ann Marie Smith in degrading circumstances in April.
Police attended the headquarters of Integrity Care in Edwardstown and its directors' home in Huntfield Heights to seize paper and electronic documents relating to Ms Smith's care.
Detective Superintendent Des Bray said while police had received "tremendous support" from the public, employees at Integrity Care were not cooperating with the investigation.
"In fact, some employees have steadfastly refused to cooperate and have done nothing whatsoever to assist the investigation and to ensure that this sort of neglect could never happen to anybody again," Superintendent Bray said.
Ms Smith died on April 6 from septic shock, multi-organ failure, severe pressure sores, malnutrition and issues connected with her cerebral palsy after being stuck in a cane chair for 24 hours a day in her Kensington Park home.
Her death prompted multiple inquiries, including by a state taskforce and the NDIS Quality and Safeguards Commission, which appointed former judge Alan Robertson to lead an independent review.
Her former carer, Rosa Maoine, has been charged with manslaughter.
Superintendent Bray said Integrity Care staff and directors would not answer "the simplest of questions".
"We know some employees were concerned about operating practices, and we plan to speak to more of them in the coming days," he said.
"We encourage employees to cooperate in this investigation, so we can ensure this never happens again.
"It's time for all employees, past and present, to do the right thing and speak to investigators by phoning Crime Stoppers tonight."
Police are conducting a coronial, criminal and financial investigation.
Integrity Care SA was banned from operating under the NDIS last month, but Superintendent Bray said there was evidence to suggest it may still be operating and providing care to other people.
"It could still be operating and providing care to other people," he said.
Any employees or people with information are being urged to phone detectives in a special phone-in.
