"If they weren't there [at the wreck site], that means something had to happen mid-water that caused them to lose power or radio communications," he said in interview published on Thursday.
Gallo said that the timeline of the underwater expedition suggests things went out of control already in mid-water, not on the ocean floor. Communication with the submarine was lost about an hour and 45 minutes after it immersed in water, while, the expert noted, it takes two hours to get to the bottom.
The expert also described Paul-Henri Nargeolet, one of the passengers on board the submersible, as his "best friend."
The worst case scenario is "probably a collapse - a catastrophic implosion of the sub itself which would be horrific," Gallo said, adding that he does not know how else a craft "can disappear that quickly."
If this is what happened, he said, the Titan must be close to where it last sent a signal to the surface. Some of the debris could have floated to the surface, some could have sunk to the bottom.
Additionally, The Wall Street Journal reported on Wednesday, citing OceanGate’s emails, that the company planned to collect DNA samples from the ecosystem around the wreck of the Titanic.
Aaron Newman, an investor in OceanGate who visited the wreck site with the Titan in 2021, told CNN the vessel is designed to return to the surface 24 hours after the dive by dropping ballast.
On Sunday, OceanGate’s submarine went missing during an expedition to the Titanic wreckage in an area about 900 miles east of Cape Cod in the North Atlantic, at a depth of approximately 13,000 feet. The submarine has a capacity for five people and an oxygen supply that can last for 96 hours. A search and rescue operation has been underway since Monday morning. The US Coast Guard said the submarine, if it is not damaged and is still functioning, will run out of air at 10.30 GMT on Thursday.
Hamish Harding, a billionaire and adventure traveler, Shahzada Dawood, vice chairman of Pakistan’s Engro corporation , and his son Suleman, have been confirmed to be on board the submersible. Media reported that the two other passengers are the CEO of OceanGate himself, Stockton Rush, and Paul-Henri Nargeolet, a French maritime expert who took part in over 35 dives to the Titanic wreck site.