FLORENCE, Italy — US student Amanda Knox’s defense got a boost on Wednesday when a new DNA test on a kitchen knife failed to prove it was the murder weapon used to kill her British roommate.
An expert witness testified that the minuscule DNA trace on the knife handle near the blade showed ‘‘considerable affinity’’ with Knox’s own DNA.
That confirmed what was already known from two previous trials: that Knox’s DNA was on the knife handle, identified through another trace.
No DNA belonging to the slain British student, Meredith Kercher, was identified. Previous genetic evidence on the blade linked to Kercher had been contested at earlier stages.
Outside the court, Knox defense lawyer Carlo Dalla Vedova said the testimony confirms his contention that the knife was used by Knox solely for preparing food. ‘‘The report confirms that this is a kitchen knife. It is not a murder weapon,’’ Dalla Vedova said.
Luca Maori, a defense lawyer for Knox’s co-defendant Raffaele Sollecito, said the trace’s very existence 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.’’
Prosecutors deferred comment for their summations, due later this month.
Knox and Sollecito were convicted in 2009 in the brutal slaying of Knox’s 21-year-old roommate in the apartment their shared in Perugia and were sentenced to 26 and 25 years in jail, respectively.
The conviction was overturned on appeal in 2011, freeing Knox after four years in jail to return to the United States, where she remains for the latest appeal. She is a student at the University of Washington.
Italy’s highest court ordered a fresh appeals trial, blasting the acquittal as full of contradictions and questioning failures to retest the DNA trace with new technology.