MILAN, Italy - The Italian appeals court that reinstated the conviction against Amanda Knox in her roommate's 2007 murder said in a lengthy reasoning made public Tuesday that Knox herself delivered the fatal blow, and that overwhelming physical evidence precluded any need to determine a clear motive.

Presiding Judge Alessandro Nencini concluded in a 337-page document that the evidence "inevitably leads to the upholding of the criminal responsibility" against Knox and her former Italian boyfriend Raffaele Sollecito for the murder of 21-year-old Meredith Kercher in a hillside villa in the university town of Perugia.

The judge said the nature of Kercher's wounds inflicted by two knives and the absence of defensive wounds indicated multiple aggressors were to blame, also including Rudy Hermann Guede, an Ivorian man convicted separately and serving a 16-year sentence.

Nencini presided over the panel that reinstated the guilty verdicts against Knox and Sollecito in January, handing Knox a 281/2-year sentence. Sollecito faces 25 years.

The release of the court's reasoning opens the verdict to an appeal back to the supreme Court of Cassation. If it confirms the convictions, a long extradition fight for Knox is expected.

She has been in the United States since 2011, when her earlier conviction was overturned.

The judge said relations between Knox and Kercher were strained, despite Knox's attempts to downplay tensions during the trial.

He also cited as credible Guede's statements that the British student had accused Knox that evening of stealing rent money.