PERUGIA, Italy — Prosecutors on Saturday requested life in prison for an American student and her ex-boyfriend accused in the fatal stabbing of her British roommate during a drug-fueled sex game – charges the U.S. woman dismissed as "pure fantasy." In their closing arguments, the prosecutors said Amanda Knox and Italian Raffaele Sollecito should be convicted on charges of murder and sexual violence for the 2007 slaying of Meredith Kercher. They deny wrongdoing. Knox, who is from Seattle, took a deep breath when Prosecutor Giuliano Mignini requested life imprisonment – Italy's stiffest punishment.