Rome (CNN) -- An Italian court says it convicted Amanda Knox and her former boyfriend of murdering her onetime roommate in part because of evidence showing that more than one person killed the British student. The Florence appeals court released its explanation Tuesday, less than three months after it convicted Knox and Raffaele Sollecito in Meredith Kercher's 2007 death in a retrial. In the more than 300-page document, the court said that a third person convicted in the murder, Rudy Guede, did not act alone, and cited the nature of the victim's wounds. Ruling Judge Alessandro Nencini, who presided over the second appeal in the case, said Kercher, 21, and Knox disagreed over the payment of the rent in the house they shared in Perugia and that "there was an argument, then an elevation and progression of aggression."
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NEW: "I am innocent," says Amanda Knox
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She was first convicted of murder in 2009
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Knox's former boyfriend, Raffaele Sollecito, was also convicted
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An appeals court overturned the convictions in 2011
Now that the explanation of the verdict has been released, defense lawyers have 90 days to appeal to @placeholder's high court.