An Italian news agency says a coroner and defense consultant has testified in the trial of American Amanda Knox that a knife believed to have been used in the slaying of a British student is "not compatible" with the victim's stab wound.

The ANSA news agency said Carlo Torre testified Monday in the trial of Knox and co-defendant Raffaele Sollecito for the 2007 death of Meredith Kercher in Perugia, central Italy. They deny wrongdoing.

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Torre testified the neck wound was made with a knife with a 3-inch (8-centimeter) long blade, while prosecutors maintain a 6 1/2-inch (16.5 centimeters) knife found at Sollecito's home could be the murder weapon.

He also said there is no evidence that Kercher was assaulted by more than one person. Torre was called by Knox's defense.