A manslaughter investigation has been opened into the deaths of seven people in the sinking of a luxury yacht off the coast of Sicily, an Italian prosecutor says.
British tech mogul Mike Lynch and his 18-year-old daughter Hannah were among six people recovered after the Bayesian superyacht sank near Porticello about 5am local time on Monday.
The body of Canadian-Antiguan national Recaldo Thomas, who was working as a chef on the superyacht, was recovered at the scene on Monday.
Ambrogio Cartosio, public prosecutor of nearby town Termini Imerese, said in a press conference at the town's court on Saturday that his office has opened an initial investigation into manslaughter, according to a translation.
He added that they are conducting an investigation against unknown persons.
Morgan Stanley International bank chairman Jonathan Bloomer, his wife Judy Bloomer, Clifford Chance lawyer Chris Morvillo and his wife Neda Morvillo were also recovered from the wreckage.
The family of Mr Lynch and Hannah have paid tribute to their loved ones, saying: "The Lynch family is devastated, in shock and is being comforted and supported by family and friends".
The family said their thoughts are with everyone affected by the tragedy and thanked the Italian coastguard, emergency services and others who helped during the tragedy, while also requesting privacy.
Vincenzo Zagarola of the Italian Coastguard previously said the search for Hannah was not "easy or quick", comparing the sunken yacht with an "18-storey building full of water".
The bodies of all six missing passengers were taken to shore in the small fishing village of Porticello, about 18km from the Sicilian capital Palermo.
Of the 22 passengers and crew on board, 15 were rescued after escaping on to a lifeboat including Mr Lynch's wife, Angela Bacares.
The boat trip was a celebration of Mr Lynch's acquittal in a fraud case in the US.
The businessman, who founded software giant Autonomy in 1996, was cleared in June of carrying out a massive fraud relating to its $US11 billion ($A16 billion) sale to US company Hewlett Packard.
