(ROME) -- The Italian Supreme Court handling Amanda Knox's murder case released its reasoning on Tuesday and cited prosecutors' early theory that her roommate Meredith Kercher died in an "erotic game" that got out of hand -- a motive that the prosecution abandoned during the initial trial.
Knox spent four years in prison after being convicted of Kercher's 2007 murder, but an Italian appeals court threw out her murder conviction in 2011. In May, however, the Italian Supreme Court rejected the Appeals Court ruling and ordered a new trial for Knox and her ex-boyfriend Raffaele Sollecito.
The Supreme Court on Tuesday released its "motivation," a written document that spells out the court's reasoning.
The court's 74-page document reportedly indicates that the Supreme Court judges supported the prosecutors' original theory that Kercher died during a forced "erotic game" that got violent, according to the Italian news agency AGI.
The sex game gone wrong theory was initially suggested by the prosecutors, but the motive later evolved into simmering enmity between the women because Knox allegedly brought boys home late at night and was sloppy, and Kercher accused her of stealing money. The defense ended the first trial by telling the jury sometimes people commit violence without a motive.
The defense attorney for Sollecito reportedly said she is not worried about the decision.
"It is more or less what we expected," attorney Giulia Bongiorno told Italian news agency ANSA. "The Supreme Court has in fact asked for a deep analysis of the investigation and evidence. But we don't fear any further analysis."
"If there was an erotic game they should find the other protagonists as they are certainly not Raffaele Sollecito and Amanda Knox," Bongiorno said.
"The scientific evidence proves in fact that there are no DNA traces of Sollecito and Knox at the scene of the crime," she said.
Knox's lawyer, Carlo Dalla Vedova, told ABC News in April that he expects a new trial to begin in the next year. The trial is at the appellate level and will take place in Florence, Italy.
In April, Knox told ABC News' Diane Sawyer that the Supreme Court's decision to order a third trial was "incredibly painful."
"I felt like after crawling through a field of barbed wire and finally reaching what I thought was the end, it just turned out that it was the horizon," Knox said. "And I had another field of barbed wire that I had ahead of me to crawl through."
Knox does not have to return to Italy for the trial, and extradition is not currently on the table.
If she is convicted again, that ruling would be appealed up to the Italian Supreme Court.
Only if the Supreme Court upheld a guilty verdict could extradition even begin.
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