Lynch and six other people were killed when the British-flagged Bayesian, a 56m-long yacht, capsized and went down on Aug 19 within minutes of being hit by a pre-dawn storm while anchored off northern Sicily.

Yesterday, the boat’s 51-year-old captain James Cutfield, a New Zealander, was put under investigation for manslaughter and shipwreck.

Cutfield declined to respond to prosecutors during questioning today.

Ship engineer Tim Parker Eaton and sailor Matthew Griffith are being investigated over the same crimes, the source said, adding that Parker Eaton is suspected of having failed to protect the yacht’s engine room and operating systems.

Griffith was on watch duty on the night of the incident, the source said.

Being investigated does not imply guilt and does not mean formal charges will follow.

The sinking has puzzled naval marine experts, who said a vessel 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.

Prosecutors in the town of Termini Imerese, near Palermo, have said their investigation would take time, and would require the wreck to be salvaged from the sea.

The Bayesian is lying on its right side, at a depth of around 50m.