Italian police divers resumed Tuesday their search for six individuals believed to be trapped inside the hull of a super yacht that sank in a storm off the coast of Sicily.

Among the missing are Mike Lynch, a British tech executive recently acquitted of fraud charges, his lawyer, and a key defense witness in the case.

The resting place of the luxury sailboat, off Porticello, is some 50-meters (164-feet) underwater – a depth that requires special precautions: Rescue crews said they were working in 12-minute shifts, a measure that slowed down their work to reach the cramped inside of the wreck.

The Bayesian, a 56-meter (184-foot) British-flagged luxury yacht, was moored about a kilometer (a half-mile) off Ponticello when a storm rolled in before 4 a.m. Monday. Civil protection officials said they believed the ship was struck by a tornado over the water, known as a waterspout.

Fifteen of the 22 people aboard survived, including a mother who reported holding her 1-year-old baby over the waves to save her. One body has been recovered, identified by officials as the on-board chef. Fire rescue officials have said the other six on board will be considered missing until they are located in the wreckage.

Karsten Borner, the captain of the Sir Robert Baden Powell, which rescued the survivors who managed to get into a lifeboat, said he was close enough to be able to see the Bayesian as the weather came in but found it had disappeared after the storm cleared.

"They said they went flat on the water and were sunk in two minutes," Borner said, quoting the survivors.

The rotating search teams, each made up of two specialized cave divers, worked Tuesday to open up access points to get inside the wreck, which lies at a depth far beyond what most recreational divers are certified to reach.

The divers have not yet been able to access the below-deck cabins because they were blocked by furniture that had shifted during the violent storm. Rescue crews said they assume the missing six are in those cabins because the storm struck when most would be sleeping, but the teams haven't verified their presence there through portholes.

Luca Cari, a spokesman for the rescue teams, said the search was proceding much more slowly than another big shipwreck in Italy, the 2012 Costa Concordia cruise ship that flipped on its side off Tuscany's coast, because of the depth of the wreck and the space divers have to maneuver.

"That was much simpler. Here everything is more tight," he said.

Among those missing was Mike Lynch, who was once hailed as Britain’s king of technology. His wife, Angela Bacares, survived.