Ten passengers have died from the virus with many more infected, including at least one person from the Illawarra.

NSW Police Commissioner Mick Fuller said the investigation, which would have oversight from the NSW Coroner' office, would rely on emails, text messages, doctors reports and exchanges with the ship's captain.

As well as the thousands of passengers who had a first hand account of the ship's health measures.

Read more: Health minister urges holiday makers to stay away from South Coast as cases rise

"There is clear evidence COVID-19 has been brought off the ship," Commissioner Fuller said at a press conference on Sunday.

"We know 10 people who have come off the Ruby Princess in Australia have lost their lives.

"There seems to be absolute discrepancies between the information provided by Carnival and what I would see is the benchmark for the laws the federal and state governments put in place to protect Australians when coronavirus started."

Commissioner Fuller said the 10 deaths of cruise passengers as well as any person's death who was infected by a passenger would be part of the investigation.

An Illawarra Shoalhaven Local Health District spokesperson confirmed the death of a 75-year-old man from complications related to COVID-19 on Friday.

The patient, who was diagnosed then admitted to Wollongong Hospital, was a passenger of Ovation of the Seas, operated by Royal Caribbean International.

The police investigation will only focus on the Ruby Princess ship.

Commissioner Fuller said there were still many "unanswered questions" as the investigation had only just begun, and would look into the actions of the cruise liner, Port Authority of NSW, ambulance, police and the NSW Health department.

Commissioner Fuller said early indications were that police, ambulance and Port Authority of NSW had done an "fantastic job" after being advised, via a Triple 0 call, from a member of the crew that two passengers needed medical assistance.

"Port Authority of NSW did a fantastic job," he said. "They made contact with ship, stopped it coming into harbour, made contact with operators who informed them COVID-19 was not an issue.

"The investigation will look into the actions of every agency."

Commissioner Fuller said a criminal investigation was the only way to found out if national biosecurity laws or state laws had been broken.

Any criminal negligence of those involved would also be investigated.

"I have received a letter through the Premier's office from Carnival Australia saying they will give me any information I need going forward, which is wonderful," he said.

"There will be lessons learnt, I have no doubt about that."

Commissioner Fuller said remaining crew members on the Ruby Princess were being taken off the ship if they needed medical attention.

The ship had become a "hospital", with the cruise liner managing the majority of sick crew members as isolation continued on the ship.

"No one has been denied medical assistance and no one will be denied that assistance," he said.

"Almost 200 crew members are showing symptoms and part of the process is swabbing them to find out if they have the virus.

"All [crew members] have been stablised and are in good condition."

Commissioner Fuller said the goal was to find a safe port and dock the ship so medical attention could be provided more easily, as well as evidence collected.

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