MILAN (AP) — Italian prosecutors appealed Tuesday to Italy’s highest criminal court against the overturning of the murder convictions of American Amanda Knox and her former boyfriend in the brutal slaying of a British student.

Perugia prosecutors filed the 111-page appeal more than four months after an appeals court in Perugia threw out the convictions against Knox, 24, and Raffaele Sollecito, 27.

The appeal, which was expected, marks the third and final stage in the criminal case against Knox and Sollecito for the Nov. 1, 2007 stabbing death of Meredith Kercher, a 21-year-old British student studying in the hilltop town of Perugia.

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.

Luca Maori, Sollecito’s lawyer, said the high court is expected to issue its decision toward the end of the year.

The prosecutors move was expected, and Maori said he would file his counter-arguments after going over the prosecutors’ appeal.

“We will write our brief to say it’s a mistake,” Maori 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.

Kercher was found slain in a pool of blood in the house she shared with Knox in Perugia. The appeals court in October said the guilty verdicts against the pair were not corroborated by any evidence, and that the court hadn’t proven they were in the house when Kercher was killed.

Still, the appellate panel stopped short of saying what might have happened the night of the murder.

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.