Amanda Knox slams Italian court, vows new appeal

SEATTLE - Amanda Knox says an Italian appeals court's reasons for reinstating the murder conviction against her in the 2007 killing of her roommate, Meredith Kercher, are not supported by evidence or logic.

WATCH: 48 Hours: Amanda Knox's Untold Story

On Tuesday, the court issued its explanation for reinstating Knox's conviction, saying it was she who delivered the fatal knife blow to 21-year-old Meredith Kercher in Perugia, Italy.

Knox was first convicted, then acquitted on appeal, in Kercher's slaying. The acquittal was vacated last year by Italy's highest court, which ordered a new appeals trial, and she was convicted again.

In a written statement Knox said, "I am innocent." She said forensic evidence refutes the appeals court's theory that more than one person attacked Kercher and that a small kitchen knife was used in the murder.

"The recent motivation document does not - and cannot - change the forensic evidence: experts agreed that my DNA was not found anywhere in Meredith's room, while the DNA of the actual murderer, Rudy Guede, was found throughout that room and on Meredith's body," Knox said.

She pointed out that the Italian courts have repeatedly changed the supposed motives for the murder -- and she said none of them hold water.

"No fewer than three motives have been previously advanced by the prosecution and by the courts. Each of these theories was as unsupported as the purported motive found in the new motivation document, and each of these alleged motives was subsequently abandoned by the prosecution or the courts," Knox said.

Knox thanked her supporters for believing in her and said she will appeal again to Italy's Supreme Court.