Prosecutors went on the offensive Tuesday at a trial hearing allegations that Prime Minister Silvio Berlusconi paid for sex with a 17-year-old girl and abused the powers of his office to hush it up. \"It\'s clear that there were people who were prostituting themselves\" during raunchy parties at Berlusconi\'s luxurious villa near Milan last year, the lead prosecutor in the case, Ilda Boccassini, said at the hearing. She also fought back against claims by Berlusconi\'s lawyers made at the last hearing that the court did not have the powers to try the prime minister. The trial over Berlusconi\'s alleged involvement with nightclub dancer Karima El-Mahroug, nicknamed \"Ruby the Heart Stealer\", began on April 6. Boccassini said that Berlusconi had \"committed a common law crime and not a ministerial crime, by abusing his powers\" as prime minister when he called a police station in May last year to have Ruby sprung out of police custody. His lawyers had argued that Berlusconi should go before a special ministerial court for the abuse of power charge and that the prostitution charge should be examined by a court close to Berlusconi\'s villa. \"Everything began in Milan and finished in Milan,\" Boccassini said. The three judges hearing the case are due to declare on July 18 whether the Milan tribunal is competent to hear the case.