Rome, April 20 - The supreme Court of Cassation on Thursday began hearing appeals in the case of captain Francesco Schettino, sentenced by two lower courts to 16 years in jail for culpable homicide in the January 2012 Costa Concordia cruise liner disaster that killed 32 people. Florence prosecutors say the sentence is too short, having asked for 27 years in their appeal trial. Schettino's lawyers are asking for an acquittal. A verdict is expected at the next hearing on May 12, judicial sources said Thursday. The eventual death toll from the disaster rose to 33 when a diver died. Cassation Court prosecutor-general Francesco Salzano on Thursday asked Italy's top appeals court to uphold Schettino's sentence of 16 years and one month, but also said the term might be raised given the seriousness of his actions that night. The Tuscan island of Giglio on January 13 marked the fifth anniversary of the Costa Concordia shipwreck, as it has done each year since 2013, with a special Mass, the sounding of boat sirens and a torchlight procession in memory of the 32 people who died in the disaster off its coast. Schettino had brought the liner close to the coast to "salute" officials on land. With 3,216 passengers and 1,013 crew members aboard, the cruise ship hit an underwater rock formation off the island's east coast just south of its port at 21:45 on the evening of Friday, January 13, 2012, in a strong impact that opened a hole 70 metres wide on the left side of its hull. The ship's captain, Schettino, had decided to "navigate according to his sailor's instinct, closer to the island, trusting in his abilities", wrote judges in the subsequent trial sentence, in which he was given 16 years and one month in prison. The ship ran aground north of the island's port at Punta Gabbianara, which saved it from sinking 100 metres to the sea floor. In addition to the 32 people who were killed in the disaster, an additional 157 people were injured. Schettino lost an initial appeal on May 31 of last year, and received an additional five-year ban on practicing any maritime profession. His defence team appealed to the Cassation Cassation to annul the sentence. Schettino was the only person to stand trial for the disaster after a number of crew members and company staff reached plea bargains with prosecutors and were sentenced to three years each.