Prosecutors have asked Italy's highest criminal court to reinstate the murder convictions of Amanda Knox and her former boyfriend for the murder of British student Meredith Kercher.
They lodged the appeal more than four months after a lower appeal court threw out the convictions against Knox, 24, and Raffaele Sollecito, 27.
Prosecutor Giovanni Galati said he is "very convinced" that Sollecito and Knox are responsible for stabbing to death 21-year-old Miss Kercher, who shared an apartment with Knox in the university town of Perugia.
Mr Galati said that the appeals sentence must be thrown out, saying it was full of "fuelledomissions and many errors".
The appeal, which was expected, marks the third and final stage in the criminal case against Knox and Sollecito.
The two were found guilty in a lower court of killing Miss 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.
Luca Maori, Sollecito's lawyer, said the high court is expected to issue its decision toward the end of the year.
Mr Maori said he would lodge his counter-arguments after going over the prosecutors' appeal.
"We will write our brief to say it's a mistake," he said.
The high court cannot hear new evidence, and will make its decision based on what has been submitted in earlier trials.
The fatal blow to the prosecution's case was a court-ordered DNA review in the appellate trial that discredited crucial genetic evidence used to convict Knox and Sollecito in 2009.
The court in October said the guilty verdicts against the pair were not corroborated by any evidence, and that the court had not proved they were in the house when Miss Kercher was killed.
A third defendant, Ivory Coast-born drifter Rudy Guede, was convicted in a separate trial of sexually assaulting and stabbing Miss Kercher. His 16-year sentence, reduced in appeal from an initial 30 years, was upheld by Italy's highest court in 2010.Reuse content