Italian prosecutors are investigating the sinking of Mike Lynch's superyacht as manslaughter

Italian prosecutors in Sicily announced on Saturday an investigation into possible crimes of negligent shipwreck and manslaughter following the sinking of a luxury yacht off the coast that killed seven people, including British tycoon Mike Lynch.

The Bayesian, a British-flagged superyacht, sank in a matter of minutes last Monday about 700 meters from the port of Porticello, near Palermo, after being hit by a waterspout caused by a cold wave.

"The Prosecutor's Office of Termini Imerese has filed a case with the State against unknown persons, for possible crimes of negligent shipwreck and multiple homicide by negligence," prosecutor Ambrogio Cartosio told the press.

He warned however that the investigation is at an early stage, as the last body, that of the 18-year-old daughter of the tech mogul Hannah Lynch, was just recovered on Friday.

"At this stage, precisely because the investigation can evolve in one direction or another, we are not ruling out anything at all," he specified.

Lynch, 59, had invited friends and family to the ship to celebrate his recent acquittal in a massive U.S. fraud case.

In June, a San Francisco court acquitted the British billionaire of all charges in connection with an $11 billion fraud involving the sale of his company Autonomy to the Hewlett-Packard Group.

His 56-meter luxury sailing yacht was struck by a waterspout early Monday morning while anchored off Porticello.

Fifteen people were rescued and soon after the body of a man was found, who on Saturday was confirmed to be the ship's cook.

A major search operation with diver specialists found the bodies of four of Lynch's friends on Wednesday and Lynch himself on Thursday.

The speed at which the sailboat sank and the fact that other vessels around it were unaffected raised questions, particularly about whether the ballasted keel, which acted as a counterweight to the imposing 75-meter mast, was lowered or raised at the time of the storm.

In an interview with the Italian news outlet Corriere della Sera, the head of The Italian Sea Group and owner of the Perini Navi shipyard that built the Bayesian, pointed out human error.