FLORENCE, Italy >> In the third Italian murder trial of U.S. student Amanda Knox, a court-appointed expert testified today that the alleged murder weapon shows a new DNA trace that belongs to Knox and not the victim.

That testimony bolsters the defense, which claims the kitchen knife was not the weapon used in the bloody 2007 slaying of Knox’s British roommate, 21-year-old Meredith Kercher.

Another piece of DNA on the knife blade initially attributed to Kercher was disputed on appeal.

Expert Andrea Berti testified Wednesday that the minute new DNA trace from the knife’s handle showed "considerable affinity" with Knox’s DNA, while not matching those of Kercher, Knox’s co-defendant Raffaele Sollecito or Rudy Guede, an Ivorian man who has been convicted separately in the brutal slaying.

Knox defense lawyer Luca Maori told the Associated Press after the hearing that expert testimony backs their argument that Knox had used the knife found in Sollecito’s kitchen solely for preparing food. He also noted that the new DNA trace was from the knife handle where another DNA piece linked to Knox had been located.

"It means that Amanda took the knife exclusively for cooking matters, to keep in the kitchen and to use it," Maori said.

Maori said the trace’s very existence also indicated the knife had not been washed.

"It is something very important," he said. "It is absurd to use it for a murder and put it back in the drawer."

The DNA evidence on the knife found in a drawer at Sollecito’s place has been among the most hotly contested evidence in the original trial and now in two appeals.

Knox and Sollecito were convicted in 2009 of murdering Kercher, and sentenced to 26 and 25 years in jail, respectively. The conviction was overturned on appeal in 2011, freeing Knox to return to the United States where she remains for the latest appeal.

Italy’s highest court, however, ordered a fresh appeals trial, blasting the acquittal as full of contradictions. It specifically cited the Perugia appeals court’s failure to test the tiny trace on the blade, especially in light of advanced technology, as one of the errors that led it to vacate the acquittals.

Prosecutors contend the knife was the murder weapon because it matched Kercher’s wounds, and presented evidence in the first trial that it contained Kercher’s DNA on the blade and Knox’s on the handle.

However, a court-ordered review during the first appeal in Perugia, where the murder happened, discredited the DNA evidence. It said there were glaring errors in evidence-collecting and that below-standard testing and possible contamination raised doubts over the DNA traces linked to Kercher on the blade, as well as Sollecito’s DNA on Kercher’s bra clasp.

Sollecito addressed the court on Wednesday, as allowed by the Italian judicial system, acknowledging that he hadn’t taken seriously enough the accusations at the beginning because he was too caught up with his new romance with Knox to grasp what was happening.

"Me and Amanda were living the dawn of a carefree romance and we wanted to be completely isolated in our love nest," Sollecito said.

He struggled with his composure as he pleaded with the court to acquit him.

"I hope I’ll have the chance to live a life, a life, because at the moment I don’t have a real life," he said. "That’s what I’m asking you."

The DNA trace is the last new evidence to be entered in the latest trial. Prosecutors begin their summing up later this month, followed by the defense in December. A verdict is expected in January.