TERMINI IMERESE, Italy >> An Italian prosecutor has opened a manslaughter investigation into the deaths of British tech magnate Mike Lynch and six other people who were killed when a luxury yacht sank in stormy weather off Sicily this week.

The head of the public prosecutor’s office of Termini Imerese, Ambrogio Cartosio, said that while the yacht had been hit by a very sudden meteorological event, it was “plausible” that crimes of multiple manslaughter and causing a shipwreck through negligence had been committed.

So far the investigation was not aimed at any individual person, he told a news conference.

Lynch’s 18-year-old daughter, Hannah, was also among those who died when the family’s 56-metre-long (184-foot) boat, the Bayesian, capsized during a fierce, pre-dawn storm on Monday off Porticello, near Palermo.

Fifteen people survived, including Lynch’s wife, whose company owned the Bayesian, and the yacht’s captain.

The disaster would be even more painful if the investigation showed it was caused “by behaviours that were not aligned to the responsibilities that everyone needs to take in shipping,” Cartosio said.

The captain James Cutfield and the other survivors have been questioned this week by authorities. None of them have commented publicly on how the ship went down.

Raffaele Cammarano, another prosecutor speaking at the same news conference, said that when authorities questioned Cutfield he had been “extremely cooperative”.

The sinking has puzzled naval marine experts who say a boat like the Bayesian, built by Italian high-end yacht manufacturer Perini, should have withstood the storm and in any case should not have sunk as quickly as it did.

Pulling the Bayesian out of the sea will help investigators determine what happened, but the operation is likely to be complex and costly. The wreck is lying apparently intact on its side at a depth of 50 metres (164 feet).

“It’s in the interests of the owners and managers of the ship to salvage it,” Cartosio said, adding “they have assured their full cooperation”.

Giovanni Costantino, CEO of The Italian Sea Group , which owns Perini, told Reuters this week the shipwreck was the result of a string of “indescribable, unreasonable errors” made by the crew, and ruled out any design or construction failings.

Cammarano said the meteorological event that hit the vessel was most likely a “downburst”, a very strong downward wind that is an intense but relatively frequent event at sea, rather than a water spout which involves rotating winds like a whirlwind or tornado.

He said that the passengers were all probably asleep at the time of the storm which was why they failed to escape.

Palermo’s Coast Guard Chief Raffaele Macauda, who attended the press conference, said there was no specific ban for the ship to be anchored where it was struck by the storm, as weather bulletins at the time were not reporting a major storm alert for the wide area of the southwestern Tyrrhenian Sea.

SEARCH FOR BODIES

Cartosio did not rule out that someone could be put under investigation before the ship is salvaged, on the basis of other evidence.

He said there was no legal obligation for the captain, crew and passengers to remain in Italy but authorities expected them to cooperate with the probe.

The prosecutor said it had not been possible to carry out alcohol or drug tests on the survivors as they were in a state of shock and needed treatments for injuries.

In the yacht, the bodies of the dead were found in the cabins on the left-hand side of the boat, where the passengers may have tried to search for remaining bubbles of air, the head of Palermo’s Fire Brigade, Girolamo Bentivoglio Fiandra, said during Saturday’s news conference.

Divers scoured the submerged vessel all week to recover bodies, with Hannah Lynch’s the last to be recovered on Friday. The five other dead passengers were recovered on Wednesday and Thursday, while the body of the only crew member who died, onboard chef Recaldo Thomas, was found on Monday.

Mike 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 U.S. fraud trial.

Among those who also died in the wreck were Lynch’s lawyer Chris Morvillo and Jonathan Bloomer, a Morgan Stanley banker who had appeared as a character witness in the case on his behalf.