5th body recovered from Mike Lynch's family yacht off Sicily

 Divers recovered the body of a fifth victim of the Bayesian superyacht wreck Thursday morning, Sicily Civil Protection Chief Salvo Cocina confirmed to CBS News, and the Reuters news agency cited Italian Interior Ministry official Massimo Mariani as saying it was the body of Mike Lynch, the British tech magnate whose wife owned the vessel.

Italian Coast Guard spokesperson Vincenzo Zagarola told CBS News that teams were still working to recover the body of the sixth and final person left missing when the boat went down. The six bodies had remained stuck inside the 184-foot luxury yacht for days after it sank early Monday morning off the coast of Palermo, Sicily in a severe thunderstorm.

Four bodies were retrieved Wednesday from the Bayesian, which was resting on the seafloor at a 90 degree angle at a depth of over 160 feet. The vessel's position and items that moved around inside the ill-fated yacht made recovery efforts slow and hazardous.

Italian authorities have not officially identified the remains recovered from the Bayesian, which belonged to Lynch's wife Angela Bacares. She was among the 15 people who managed to escape from the boat as it sank quickly on Monday morning, but Lynch and his 18-year-old daughter Hannah were among those left missing.

Another victim, the Bayesian superyacht's chef, was found dead soon after the boat capsized.

Along with Lynch and his daughter, the technology mogul's American lawyer Chris Morvillo and his wife Neda, and British banker Jonathan Bloomer and his wife, were believed to have been trapped in the yacht when it sank.

Questions as to how the state-of-the-art boat could have gone down so quickly have mounted steadily since the accident.

Italian media were reporting Thursday that, after questioning survivors and witnesses, Italian prosecutors had opened an official investigation into a possible "culpable shipwreck." No individuals had been named as potential suspects.

On Thursday, Giovanni Costantino, head of the Italian Sea Group, which owns the company Perini Navi, which built the Bayesian in 2008, blamed human error.

"A Perini ship resisted Hurricane Katrina, a Category 5 [hurricane]. Does it seem to you that it can't resist a tornado from here?" he remarked to the newspaper Corriere della Sera. "It is good practice when the ship is at anchor to have a guard on the bridge, and if there was one he could not have failed to see the storm coming. Instead, it took on water with the guests still in the cabin. ... They ended up in a trap, those poor people ended up like mice."

One possible factor could have been that the ship's keel — a fin-like structure that sticks out from the bottom of the boat, designed to provide stability and counterweight to the huge mast — was not fully deployed. The yacht had a retractable keel that could be raised for entry into shallow harbors. But a raised keel at sea would have made the ship much more vulnerable to instability in the strong winds that struck early Monday morning.

When asked whether divers had seen the ship's keel in a raised position, a spokesman for the Italian Coast Guard told CBS News that only the prosecutor investigating the incident could confirm such information but that the Coast Guard "was not denying" it.

The ship's captain, 51-year-old New Zealand national James Cutfileld, was questioned for two hours by prosecutors on Thursday, according to Italian media.