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

The Court of Cassation ruled Tuesday 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.

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.