The cruise ship is docked at a port in southern New South Wales.
The New South Wales (NSW) Police earlier announced a criminal investigation into the Ruby Princess, which is owned by Carnival Corp, after its 2,700 passengers were allowed to disembark in Sydney on March 19 despite some of them exhibiting flu-like symptoms. Fifteen among them died later after contracting the illness, Sydney Morning Herald reported.
Detectives wearing Personal Protective Equipment (PPE) boarded the vessel at Port Kembla on Wednesday night to gather evidence about how hundreds of passengers aboard were allowed to deboard the ship last month.
"Strike Force Bast investigators are conducting inquiries on-board the Ruby Princess this evening," NSW Police said in a statement on Wednesday.
"The operation is being conducted under the strictest health and workplace safety guidelines," it read.
In the coming days, police will interview other high-priority witnesses about the scandal, while the vessel is expected to remain at Port Kembla for 10 days with 1,040 crew members undergoing medical assessments, the statement said.
About 200 crew members of the ship have shown symptoms of coronavirus, while 18 others have tested positive so far.
NSW Police Commissioner Mick Fuller on Thursday said about three-quarters of the Ruby Princess crew members had indicated they wish to remain onboard the ship.
"Ships have a black box very similar to that of international planes and that and other evidence has been seized for further investigation, and that is just sort of part one of the investigation," Fueller added.
The total number of cases in NSW stands at 2,773. Some 31 coronavirus patients are in intensive care.
The NSW Health Department has said that there are 36 travellers currently in hotel quarantine who have tested positive to COVID-19 and 121 quarantined travellers showing coronavirus symptoms.
NSW Premier Gladys Berejiklian warned about surging cases of community transmission and stressed on the necessity to practice social distancing until a vaccine or medicine is found to ward off the contagion.
( With inputs from ANI )