Amanda Knox was ordered to stand trial again for the murder of her roommate by Italy's top criminal court on Tuesday, but there appeared to be little the country could do to force her to return for the new hearings.
The Court of Cassation, Italy's final court of appeal, overturned the acquittals of both Knox and her then-boyfriend Raffaele Sollecito over the 2007 killing of British student Meredith Kercher.
In a statement responding to the decision, Knox slammed prosecutors and vowed to fight on.
"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," said Knox, who is now aged 25 and living in the Seattle area.
"I believe that any questions as to my innocence must be examined by an objective investigation and a capable prosecution," she added. "The prosecution responsible for the many discrepancies in their work must be made to answer for them, for Raffaele's sake, my sake, and most especially for the sake of Meredith's family. Our hearts go out to them."
Knox said that she and her family would “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."
Kercher, 21, died from knife wounds in an apartment that she shared with Knox in Perugia, Italy.
Prosecutors argued that Knox and Sollecito killed her after a drug-fueled sexual assault in a case that drew worldwide attention.
Young, attractive and with a seemingly bright future, the prosecution’s allegations suggested Knox’s outward appearance belied a secret, more sinister nature.
Knox was routinely referred to by a nickname "Foxy Knoxy" in newspapers as every detail of her life was examined.
She and Sollecito, who turned 29 on Tuesday, were prosecuted and found guilty of killing Kercher. Knox was sentenced to 26 years in prison, while Sollecito got 25, but they were acquitted after serving four years.
Small-time drug dealer Rudy Hermann Guede, who knew Knox, was convicted and given a 16-year sentence.
Meredith’s sister Stephanie Kercher, 29, told Britain's ITV News that the family welcomed the court's decision to retry Knox and Sollecito "in the sense that we hope to find the answers."
"We are never going to be happy about any outcome because we have still lost Meredith, but we obviously support the decision and hope to get answers from it," she said. "There are still so many unanswered questions, all we have ever wanted to do is do what we can for Meredith and to find out the truth of what happened that night."
"Rudy Guede's conviction was on the basis that there was more than one person there so that is something that needs to be looked into," she added.
Francesco Maresca, a lawyer representing Kercher's family, said in a statement on Monday that the acquittals were "defective" and "lacked transparency," Reuters reported.
"There was a lot of external pressure and the judge showed a will from the start to acquit," Maresca said.
Italian law cannot compel Knox to return to Italy and she could be tried in absentia.
Knox’s attorney, Theodore Simon, told TODAY that the student and her family were confident her acquittal would be upheld.
He characterized the outcome of Tuesday’s court decision as a "revision" of the case, as opposed to a retrial, saying: "Merely because they have sent it back for revision does not mean that anything else will happen other than she will be recognized as not guilty and the same thing will happen again."
“From what I understand, [Court of Cassation judges] have sent [the case] back for revision and reconsideration. They will review it. They may simply affirm that there was a ‘not guilty’ before and it should remain the same. They may seek to take some further evidence, but nothing has really changed.”
Simon said there was no reason for Knox to have to return to Italy, saying her presence was "no issue" in Tuesday’s ruling.
The Italian appellate court hearing the case could declare her in contempt of court but that carries no additional penalties.
"If the court orders another trial, if she is convicted at that trial and if the conviction is upheld by the highest court, then Italy could seek her extradition," another of Knox's lawyers, Carlo Dalla Vedova, told The Associated Press.
Since her release from prison in 2011, Knox has resumed her studies in Seattle.
Knox's book about the case is due to be released in April.
Reuters and The Associated Press contributed to this report. ITV News is the U.K. partner of NBC News.