Experts have recovered "presumed human remains" from the remains of the Titan sub, which imploded during a dive to the Titanic wreck, the US Coast Guard said.
"United States medical professionals will conduct a formal analysis of presumed human remains that have been carefully recovered," the agency said in a statement on Wednesday after parts of the wreckage were unloaded in eastern Canada.
Debris from the Titan submersible was returned to land on Wednesday.
The return of the debris to port in St John’s, Newfoundland and Labrador, is a key piece of the investigation into why the submersible imploded.
"I am grateful for the coordinated international and interagency support to recover and preserve this vital evidence at extreme offshore distances and depths," US Coast Guard Chief Captain Jason Neubauer said in a statement.
"The evidence will provide investigators from several international jurisdictions with critical insights into the cause of this tragedy. There is still a substantial amount of work to be done to understand the factors that led to the catastrophic loss of the TITAN and help ensure a similar tragedy does not occur again."
Debris from the Titan was located about 3,810 metres underwater and roughly 488 metres from the Titanic on the ocean floor, the Coast Guard said last week.
'Major marine casualty'
The Coast Guard is leading the investigation into why the submersible imploded during its June 18 descent.
Officials announced on June 22 that the submersible had imploded and all five people on board were dead.
One of the experts the Coast Guard consulted with during the search said analysing the physical material of recovered debris could reveal important clues about what happened to the Titan. And there could be electronic data, said Carl Hartsfield of the Woods Hole Oceanographic Institution.
"Certainly, all the instruments on any deep sea vehicle, they record data. They pass up data. So the question is, is there any data available? And I really don’t know the answer to that question," he said on Monday.
Ocean Gate CEO and pilot Stockton Rush was killed in the implosion along with two members of a prominent Pakistani family, Shahzada Dawood and his son Suleman Dawood; British adventurer Hamish Harding; and Titanic expert Paul-Henri Nargeolet.
The National Transportation Safety Board has said the Coast Guard has declared the loss of the Titan submersible to be a "major marine casualty" and the Coast Guard will lead the investigation.
OceanGate Expeditions, the company that owned and operated the Titan, is based in the US, but the submersible was registered in the Bahamas.
The OceanGate company in Everett, Washington, closed when the Titan was found.
Meanwhile, the Titan’s mother ship, the Polar Prince, was from Canada.
The operator charged passengers $250,000 each to participate in the voyage. The implosion of the Titan has raised questions about the safety of private undersea exploration operations. The Coast Guard also wants to use the investigation to improve safety of submersibles.