Rome, May 8 - Protesters were subjected to "violence and abuse" and "unspeakable behaviour" while being held at a police detention centre in the Bolzaneto barracks during the 2001 Group of Eight (G8) summit in Genoa, a prosecutor said Wednesday. During the first day of proceedings before Italy's top court, Joseph Volpe asked the Court of Cassazione to uphold sentences against 44 defendants held to be civilly responsible for violence against protesters between July 20 and 22, 2001. In total, 252 demonstrators have said they were spat at, verbally and physically humiliated or threatened with rape while being held at the centre. All 44 have appealed their convictions, including compensation orders, in proceedings that are scheduled to last three days. Only seven of the group, which includes police officers and prison doctors, have been convicted on criminal charges arising from the detention of protesters. Their sentences range from one- to three years in jail in connection with the two days of mayhem that occurred when more than 300,000 demonstrators converged on Genoa for the G8 summit in July 2001. One protester was shot dead while attacking a Carabinieri policeman, shops and businesses were ransacked, and hundreds of people injured in clashes between police and demonstrators. During a night raid by police at the Diaz school, which was being used by G8 protestors as sleeping quarters, three people were left comatose and 26 had to be taken to hospital. That attack by police gained headlines worldwide. However, almost every conviction related to police actions during the summit eventually timed out. Last October, former national police chief Gianni De Gennaro was acquitted on charges that he pressured a former Genoa police chief to commit perjury in a trial over police brutality at the G8 summit in 2001. Also acquitted on the same charges was the ex-head of the Genoa branch of Digos security police, Spartaco Mortola. The prosecution had asked for a two-year sentence for De Gennaro, who is currently the head of Italy's intelligence services, and 16 months for Mortola. Both men were accused of persuading Francesco Colucci, chief of police in Genoa in 2001, to change his testimony about the Diaz school raid. Colucci has always denied being pressured to give false testimony, saying he always told the truth in court, and has been ordered to to face a separate trial for perjury. Controversy raged in November 2011 after a verdict acquitted 16 defendants including the three top officers and sentenced 13 lower-ranked officers to terms ranging from one month to four years - terms they will never serve because of an intervening amnesty.