Updated at 8:30 p.m. ET

The Ruby Princess cruise ship docked in Sydney on March 19 and nearly 2,700 passengers who were on board left freely, though some exhibited flu-like symptoms. On Sunday, Australian police announced they've launched a criminal investigation into the Ruby Princess, citing questions over whether the operators of the ship, Carnival Australia, were transparent about sickened passengers and crew members.

More than 340 passengers have tested positive for the coronavirus, according to the New South Wales Ministry of Health. Sixteen crew members have already tested positive for the virus, according to the New South Wales Police Force, while another 200 are exhibiting symptoms. In all, at least six people from the ship have died, a Health Ministry official confirmed to NPR.

Police Commissioner Mick Fuller, speaking at a press conference, said that Australian authorities had made contact with the ship, "And on each case, they were informed that COVID-19 wasn't an issue on the ship."

"There seems to be absolute discrepancies between the information provided by Carnival and what I would see as the benchmark for the laws that the Federal Government and the State Government put in place in terms of protecting Australians from cruise ships when coronavirus had started," Fuller said. "The only way I can determine whether our national biosecurity laws or our state laws were broken is through a criminal investigation."

In a statement, a spokesman for Carnival Australia said the company would "willingly" cooperate with the investigation.

"Carnival Australia will vigorously respond to any allegations of which there must now be full disclosure and the basis for them," according to the statement.

While Fuller said there were "many unanswered questions" about the the Ruby Princess, "there is clear evidence that corona-19 has been brought off that ship."

As of Sunday, there were a total of 5,687 cases of coronavirus in Australia. At least 35 have died from the virus there, according to tracking by Johns Hopkins University.

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