(CBS/AP) MILAN - Italian prosecutors are challenging the acquittal of Amanda Knox and her ex-boyfriend in the slaying of British student Meredith Kercher.
Perugia prosecutors filed an appeal with Italy's highest criminal court on Tuesday, more than four months after an appeals court threw out murder convictions against Knox, 24, and Raffaele Sollecito, 27.
Prosecutors Giovanni Galati said he is "very convinced" that Sollecito and Knox are responsible for the Nov. 1, 2007, stabbing death of Kercher, a 21-year-old who shared an apartment with Knox in the university town of Perugia.
The prosecutors appeal was expected and marks the third and final stage in the criminal case against Knox and Sollecito.
Luca Maori, Sollecito's lawyer, said the high court is expected to issue its decision toward the end of the year. The high court cannot hear new evidence, and will make its decision based on what has been submitted in earlier trials.
The two were found guilty in a lower court of slaying Kercher in what prosecutors described as a sex-fueled attack, and sentenced to 26 years and 25 years respectively. An appeals court then said the evidence did not hold up, freeing Knox to return home to the United States after serving four years in prison. Sollecito lives in Italy.
A third defendant, Ivory Coast-born drifter Rudy Guede, was convicted in a separate trial of sexually assaulting and stabbing Kercher. His 16-year sentence, reduced in appeal from an initial 30 years, was upheld by Italy's highest court in 2010.