Prosecutors in Italy are investigating the captain of a superyacht that sank during a storm off Sicily last week, killing seven people, on possible charges including manslaughter, his lawyer said on Monday.

James Cutfield, the 51-year-old New Zealand national who was captain of the Bayesian, was among 15 survivors of the August 19 sinking that killed British tech magnate Mike Lynch, his daughter Hannah and five others.

Mr Cutfield is being investigated for possible manslaughter and culpable shipwreck, said lawyer Aldo Mordiglia, one of two attorneys appointed for the captain’s defence.

Mr Mordiglia said Mr Cutfield, who already has been questioned, would be questioned again by prosecutors on Tuesday. He declined to discuss the strategy for the defence.

Under Italian law, being under investigation does not imply guilt and does not necessarily lead to criminal charges.

On Saturday, chief prosecutor Ambrogio Cartosio confirmed an investigation has been launched.

He said his team will consider each possible element of responsibility, including those of the captain, the crew, individuals in charge of supervision, and the yacht’s manufacturer.

The Bayesian, a 184ft (56m) British-flagged luxury yacht, went down near the Mediterranean island in southern Italy last Monday.

Investigators are focusing on how a vessel deemed “unsinkable” by its manufacturer, Italian shipyard Perini Navi, sank while a nearby sailing boat remained largely unscathed.

Prosecutors said the event was “extremely rapid” and could have been a “downburst” – a localised, powerful wind that descends from a thunderstorm and spreads out rapidly upon hitting the ground.

The crew were saved, apart from the chef, while six passengers were trapped in the hull.