The appeals court questioned the conclusion about the DNA on the knife and said the bra clasp wasn't collected as evidence until 46 days after the murder when the crime scene had been disturbed several times. The appellate ruling said it was possible the clasp had been contaminated by other evidence.
The appeal will be heard by a panel composed of Judge Alessandro Nencini, his assistant judge and eight jurors, five women and three men. Over 200 media passes have been requested and TV cameras are being kept outside the building.
Rudy Guede, a young man from Ivory Coast, who was tried separately in a fast-track trial, remains in an Italian prison for the murder. Although admitting to being present at the Perugia house on the night of the murder, he has denied involvement in the crime. He is serving a 16-year sentence.
Knox told ABC News in a recent interview that she is still plagued by panic attacks and symptoms of PTSD after her 1,400 nights in an Italian prison.
The next hearing in the retrial is set for this Friday.