Amanda Knox, the American co-ed accused of the sexual assault and murder of a fellow exchange student in Italy, took the stand today in Perugia and said she was innocent. Foxy Knoxy, as the tabloid press calls her, claimed a dispute with victim Meredith Kercher over a sex toy was a "joke," and that the prosecutors' sordid version of events—a violent sexual game at the hands of Knox, her boyfriend, and another male friend—were untrue. But a mutual friend testified that, after Kercher's death, Knox told her "I know everything" and explained details of the victim's death that prosecutors say only the murderer could have known. "She died slowly and in a lot of pain," the witness alleges Knox said. Knox took the stand and, in fluent Italian, denied witnesses' accounts of her flip and sexually charged responses to learning of Kercher's death. Knox's father says his daughter's language skills improved significantly in prison.