ROME, Italy (CNN) -- An American woman and her Italian former boyfriend went on trial in Perugia Friday in the 2007 killing of a British exchange student, with reporters crowding the courtroom as proceedings began.
Both Raffaele Sollecito (left) and Amanda Knox deny charges of murder and sexual assault.
The cases of Amanda Knox, 21, and 24-year-old Raffaele Sollecito are expected to take months.
They are charged with murder and sexual assault in the November 2007 slaying of Knox's roommate, Meredith Kercher, who died in what prosecutors called a "drug-fueled sex game" with the couple and a third person, Rude Guede.
Guede was convicted of murder in October and sentenced to 30 years in prison. He is expected to be one of about 100 witnesses in the case.
Kercher was found dead in her bed, half-naked, with a knife wound to her neck. In court papers, prosecutors state that Sollecito held Kercher by her wrists while Knox poked at her with a knife and Guede sexually assaulted her.
Prosecutors say they have physical evidence placing the defendants at the scene, and that they gave investigators confusing and contradictory statements about their whereabouts the night Kercher died.
Knox first said she was at the house she shared with Kercher, then changed her story, according to court records.
Sollecito, meanwhile, said he was never at the house, but was at his apartment, watching a movie on his computer with Knox. Later, he told investigators he did not remember whether Knox was with him the entire night.
Defense lawyers are expecteed to argue that the physical evidence was tainted by sloppy police work.
The case will be heard by a panel of eight judges. The trial has drawn more than 140 journalists from 86 news outlets to the courthouse in Perugia, a university town about 185 km (115 miles) north of Rome.
The presiding judge in the case, Giancarlo Massei, barred cameras from the courtroom Friday morning after initial proceedings and said he could completely close portions of the trial dealing with the most graphic sexual assault allegations.
Kercher's family requested the trial be held entirely before closed doors, an option Italian law allows in cases dealing with sexual assault. Prosecutors argued that the case should be kept open, but not televised.
The number of reporters forced court officials to seat some of them at the defense table at the start of the case.
Massei said he would allow a closed-circuit television feed into the court's press room to let reporters who couldn't get a seat watch proceedings -- a feed that would be cut if the case is closed.