Knox, 26, was sentenced in absentia to 28 years and six months in prison for the 2007 murder of British student Meredith Kercher in the latest dramatic twist in the long-running legal saga.
Both Knox and her former lover Raffaele Sollecito, who was sentenced to 25 years, have fiercely maintained their innocence and vowed to appeal.
Fighting back tears, Knox told ABC television today the court's guilty verdict "hit me like a train."
Knox, 26, spent four years in an Italian prison after being initially convicted of the murder of her roommate Kercher in Perugia, Italy, where they were both studying.
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"I did not expect this to happen. I really expected so much more from the Italian justice system. They found me innocent once before," Knox said in her first television interview since the latest verdict was announced.
"There was no evidence then and there's no evidence now," he said. "That's why it becomes so incomprehensible how could there be a different verdict when there's no new or differing evidence."
Meanwhile in Italy, Sollecito was picked up by police in the town of Venzone near the Austrian border where he was reportedly staying with his girlfriend.
Sollecito, 29, who was designated a flight risk by the court, was asked to surrender his passport after being reportedly found with Greta Menegaldo, whose parents live in South America, Italian media reported.
Sollecito had made a brief appearance in court yesterday morning, but was not present for the verdict.