A lawyer for Amanda Knox has said the US college student is "ready to fight" after Italy's top criminal court overturned her acquittal and ordered a retrial for the murder of her British room-mate Meredith Kercher.
"She thought that the nightmare was over," Knox's lawyer, Carlo Dalla Vedova, said, minutes after conveying the unexpected turn of events to his client, "but she's ready to fight."
Now a student at the University of Washington in Seattle, Knox called the decision by the Rome-based Court of Cassation "painful" but said she was confident she would be exonerated.
She left Italy a free woman after her October 2011 acquittal - but only after serving nearly four years of a 26-year prison sentence from a lower court that convicted her of murdering Ms Kercher, 21.
The exchange student's body was found in a pool of blood, her throat slit, in a bedroom of the house the two shared in Perugia, a university town 100 miles north of Rome.
Raffaele Sollecito, Knox's Italian boyfriend at the time, was also convicted of the November 1 2007, murder, then later acquitted. His acquittal was also thrown out and a new trial ordered.
Italian law cannot compel Knox to return for the new trial and Mr Dalla Vedova said she had no plans to do so.
The judicial saga is likely to continue for years and it will be months before a date is set for the new trial, to be held in Florence instead of Perugia because the small town has only one appellate court, which already acquitted her.
Prosecution and defence teams must also await details of the ruling explaining why the high court concluded there were procedural errors in the trial that acquitted Knox and Sollecito. The court has 90 days to issue its explanation.
"It was painful to receive the news that the Italian Supreme Court decided to send my case back for revision when the prosecution's theory of my involvement in Meredith's murder has been repeatedly revealed to be completely unfounded and unfair," Knox said in a statement.