ROME -- Italy's highest criminal court ordered a whole new trial for Amanda Knox and her former Italian boyfriend on Tuesday, overturning their acquittals in the gruesome slaying of her British roommate.
The move extended a prolonged legal battle that has become a cause celebre in the United States and raised a host of questions about how the next phase of Italian justice would play out.
Knox, now a 25-year-old University of Washington student in her hometown of Seattle, called the decision by the Rome-based Court of Cassation "painful" but said she was confident that she would be exonerated.
The American left Italy a free woman after the 2011 acquittal and after serving nearly four years of a 26-year prison sentence from a lower court that convicted her of murdering Meredith Kercher. The 21-year-old British exchange student's body was found in November 2007 in a pool of blood in the bedroom of a rented house that the two shared in the Italian university town of Perugia. Her throat had been slit.
Raffaele Sollecito, Knox's Italian boyfriend at the time, was also convicted and acquitted.
It could be months before a date is set for a fresh appeals court trial in Florence, which was chosen because Perugia has only one appellate court. Italian law cannot compel Knox to return for the new trial and one of her lawyers, Carlo Dalla Vedova, said she had no plans to do so.
"She thought that the nightmare was over," Dalla Vedova told reporters on the steps of the courthouse. "(But) she's ready to fight."
He spoke minutes after relaying the top court's decision to Knox by phone from the courthouse shortly after 2 a.m. local time in Seattle.
Another Knox defender, Luciano Ghirga, was gearing up psychologically for his client's third trial. Ghirga said he told Knox: "You always been our strength. We rose up again after the first-level convictions. We'll have the same resoluteness, the same energy" in the new trial.
Still, it was a tough blow for Knox, and she issued a statement through a family spokesman.
"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," she said.
Knox said the matter must now be examined by "an objective investigation and a capable prosecution."
"No matter what happens, my family and I will face this continuing legal battle as we always have, confident in the truth and with our heads held high in the face of wrongful accusations and unreasonable adversity," Knox said.
The young woman had planned to sit down with a U.S. TV network to tell her story in a prime-time special to be broadcast April 30. The exclusive ABC News interview was timed to the publication of her new book "Waiting to Be Heard."
It wasn't immediately clear if there were any plans to delay the book, given the court setback.
Dalla Vedova said Knox wouldn't come to Italy "for the moment" but would follow the case from home. He said he didn't think the new appeals trial would begin before early 2014.
Prosecutors alleged Kercher was the victim of a drug-fueled sex game gone awry. Knox and Sollecito denied wrongdoing and said they weren't even in the apartment that night, although they acknowledged they had smoked marijuana and their memories were clouded.
An Ivory Coast man, Rudy Guede, was convicted of the slaying in a separate proceeding and is serving a 16-year sentence. Knox and Sollecito were also initially convicted of the murder and given long prison sentences, but were then acquitted on appeal and released in 2011.
Whether Knox ever returns to Italy to serve more prison time depends on a string of ifs and unknowns.
Should she be convicted by the Florence court, she could appeal that verdict to the Cassation Court, since Italy's judicial system allows for two levels of appeals - by prosecutors and the defense alike. Should that appeal fail, Italy could seek her extradition from the United States.
Whether Italy actually requests extradition will be a political decision made by a new government being formed right now after last month's inconclusive national election.