Italy's highest criminal court has overturned the acquittal of Amanda Knox in the slaying of her British roommate and ordered a new trial.

Amanda Knox (R) amd her mother Edda Mellas (Stephen Brashear/Getty Images)

In a statement released by Knox family spokesman David Marriott Knox says it's "painful" to have had her acquittal of murder overturned.

The Court of Cassation ruled today that an appeals court in Florence must re-hear the case against the American and her Italian-ex-boyfriend for the murder of 21-year-old Meredith Kercher.

The two were convicted of killing Knox's roommate in 2007, but an appeals court acquitted them in 2011.

Kercher's body was found in November 2007 in her bedroom of the house she shared with Knox and other roommates in Perugia, an Italian university town where the two women were exchange students. Her throat had been slashed.

Prosecutors alleged Kercher was the victim of a drug-fueled sex game gone awry. Knox and Raffaele Sollecito denied wrongdoing. An Ivory Coast man, Rudy Guede, was convicted of the slaying in a separate proceeding and is serving a 16-year sentence.

Statement From Amanda Knox

"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. I believe that any questions as to my innocence must be examined by an objective investigation and a capable prosecution. 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. 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."

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