The body of British tech magnate Mike Lynch was retrieved on Thursday from the wreck of his family yacht that sank earlier this week off the coast of Sicily during a violent storm, a senior Italian official said.

Lynch’s 18-year-old daughter Hannah is still unaccounted for, interior ministry official Massimo Mariani told Reuters after being briefed by the emergency services.

The bodies of four other people who vanished when the boat went down were recovered from the yacht on Wednesday.

The British-flagged Bayesian, a 56-metre-long superyacht carrying 22 passengers and crew, was anchored off the port of Porticello, near Palermo, when it disappeared beneath the waves in a matter of minutes after the bad weather struck in the early hours of Monday.

Lynch, 59, was one of the UK’s best-known tech entrepreneurs and had invited friends to join him on the yacht to celebrate his acquittal in June in a major U.S. fraud trial.

His body was brought ashore in a blue body bag and driven in an ambulance to a nearby hospital morgue.

Besides Lynch and his daughter, the other people who failed to make it to safety were Judy and Jonathan Bloomer, a non-executive chair of Morgan Stanley International; Clifford Chance lawyer Chris Morvillo and his wife, Neda Morvillo; and the onboard chef, Canadian-Antiguan national Recaldo Thomas.

Thomas’ body was found near the wreck on Monday.

Fifteen people, including Lynch’s wife, survived the disaster.

Mariani said it was possible that Hannah Lynch’s body was not in the boat, but might have been swept out to sea.

The families of those missing have not yet commented.

Fire brigade spokesperson Luca Cari warned it could take time, even days, before the last missing person was found, given the difficulty divers were having in accessing all areas of the boat, which is lying on its side at a depth of 50m.

A judicial investigation has been opened into the disaster, which has baffled naval marine experts, who say a boat like the Bayesian, built by Italian high-end yacht manufacturer Perini, should have been able to withstand the storm.

Giovanni Costantino, CEO of the Italian Sea Group which owns Perini, told Italian media the Bayesian was “one of the safest boats in the world” and blamed the crew for failing to follow correct safety procedures.

The captain, James Cutfield, and his eight surviving crew members, have made no public comment on the disaster.

Challenging conditions

Specialist rescuers have been searching inside the hull of the sunken yacht for the past three days in what they said were extremely challenging conditions due to the depth and the narrowness of the places that the divers are scouring.

The fire brigade compared the efforts to those that were carried out, on a larger scale, for the Costa Concordia, a luxury cruise liner that capsized off the Italian island of Giglio in January 2012, killing 32 people.

Once the final body is recovered, experts will have to decide whether, or how, to salvage the vessel.

The CEO of Italian Sea Group said the yacht’s automatic tracking system suggested that it took 16 minutes from the moment the storm first hit to the sinking.

He said it was clear the ship took in large amounts of water, adding that investigators would need to see what doorways or hatches might have been left open, focusing notably on a main door located on the left side of the yacht.

“A Perini boat survived the Category 5 Katrina hurricane. Do you think one couldn’t survive a waterspout here,” he told Corriere della Sera newspaper, referring to a type of tornado that is believed to have hit the Bayesian.

Under maritime law, a captain has full responsibility for the ship and the crew, as well as the safety of all those aboard.

The captain of the Costa Concordia is serving a 16-year prison term for his role in the 2012 disaster after he admitted to sailing too close to underwater rocks.