An autopsy has revealed the harrowing way two victims of the Bayesian superyacht incident died after initially “surviving the sinking”.

British tech tycoon Mike Lynch’s £14 million vessel got caught in a storm off the coast of Sicily on August 18 and sank, killing seven people.Morgan Stanley boss Jonathan Bloomer and psychotherapist Judy Bloomer survived the initial sinking of the yacht.

The couple found an air bubble below the deck of the sunken boat and their autopsies now show that they suffocated after they ran out of oxygen.

Italian newspaper La Repubblica reported that their lungs were “not full of water and neither were their stomachs or trachea”.

Experts said the air bubble that initially saved the couple would have run out very quickly and filled with “toxic carbon dioxide”.

Autopsies carried out on another couple Chris and Neda Morvillo confirmed they both died by drowning, sources said on Monday. Officials found “no sign” of any other injuries which may have resulted in their deaths.

The remaining three autopsies will be completed throughout the rest of next week, this includes Mike Lynch, his teenage daughter Hannah Lynch, and Recaldo Thomas, the yacht chef.

The 14 surviving members of the crew and Lynch’s wife Angela Bacares managed to get on a life raft as the yacht was sinking in the early hours.

The captain, James Cutfield, and the crew are now being investigated by Italian police for multiple manslaughter and culpable shipwreck. The investigation does not imply guilt or mean formal charges will be brought against any of them.

Chief Prosecutor Ambrogio Cartosio said there may have been “behaviours that were not perfectly in order with regard to the responsibility everybody had.”