Investigators boarded the vessel at Port Kembla wearing protective gear to gather evidence about how passengers were allowed to leave the ship when it docked in Sydney Harbour on 19 March.
About 2700 passengers disembarked the ship without adequate health checks, with the vessel since becoming the largest source of coronavirus infections in Australia.
The ship is linked to more than 600 cases of COVID-19 and more than a dozen deaths across Australia.
Crew members have also been questioned, with police announcing on Wednesday that investigators would interview “high-priority witnesses in coming days”.
Speaking to media on Thursday, NSW Police Commissioner Mick Fuller said a black box “very similar to that of international planes” had been seized along with other evidence.
“I can confirm there’s still over 1,000 crew members on the ship,” said Fuller.
“We’re working closely with [ship owner] Carnival.
“Three-quarters at this stage say they want to remain on the ship. They feel safe on the ship. And I think that’s a good outcome.”
Of the crew members remaining on the ship, about 200 are displaying flu-like symptoms and 18 have been diagnosed with coronavirus.
Earlier this week, Fuller announced the commencement of a criminal investigation into the communications, actions and other circumstances that led to the docking and disembarking of the vessel at Sydney Harbour.
