TERMINI IMERESE, Italy (AFP)— Sicilian prosecutors said Saturday they were investigating potential crimes of negligent shipwreck and manslaughter after a superyacht sank killing seven people, including UK tech tycoon Mike Lynch.

Prosecutors stressed the investigation was at an early stage following the sinking of the British-flagged sailing boat Bayesian off the north of the Italian island in a storm early Monday.

“The Public Prosecutor’s Office of Termini Imerese has registered a file with the state against unknown persons, hypothesising the crimes of negligent shipwreck and multiple negligent manslaughter,” state prosecutor Ambrogio Cartosio told reporters.

But he cautioned that with last body — of Lynch’s 18-year-old daughter Hannah — having only been recovered on Friday, the probe was at an early stage.

“We are only in the initial phase of the investigations… At this stage, precisely because the investigation could develop in any way, we are absolutely not ruling anything out,” he said.

Lynch, 59, had invited friends and family onto the boat to celebrate his recent acquittal in a massive US fraud case.

But the 56-metre (185-foot) yacht was struck by a waterspout — like a mini-tornado — before dawn on Monday as it was anchored off Porticello, near Palermo.

Fifteen people were rescued and the body of one man, confirmed Saturday as the yacht’s cook, was found shortly afterwards.

A major search operation including specialist divers subsequently identified the bodies of four of Lynch’s friends on Wednesday, then Lynch himself on Thursday.

The businessman had been acquitted on all charges in a San Francisco court in June after he was accused of an $11 billion fraud linked to the sale of his software firm Autonomy to Hewlett-Packard.