(CNN) -- — Amanda Knox's former boyfriend Raffaele Sollecito may make a statement in an Italian court Wednesday at their retrial in the 2007 killing of the British exchange student Meredith Kercher.
Sollecito, 29, is not a witness in the case, which is being heard in an appeals court in Florence. But he is expected to make a spontaneous declaration, which is the right of any defendant in an Italian trial.
He and Knox were convicted in 2009 of murdering Kercher, 21, who was found stabbed to death in November 2007 in the villa she and Knox rented in the central Italian university town of Perugia.
Their convictions were overturned in 2011 for "lack of evidence." But Italy's Supreme Court decided last year to retry the case, saying the jury that acquitted them didn't consider all the evidence and discrepancies in testimony needed to be answered.
Both Knox, 26, and Sollecito have maintained they are not guilty.
Scared to return
The retrial began September 30 without either of them present in court. The presiding judge, Alessandro Nencini, read out the details of the case, including the conviction of Ivory Coast citizen Rudy Guede for his role in Kercher's murder.
Knox returned to her hometown of Seattle after her acquittal and has been living there since. She says she is scared to return to Italy, where she spent four years behind bars.
Sollecito was in the Dominican Republic at the start of the retrial, but he has since returned to Italy. He is not required to appear in court, but if he does, he will likely read a written statement.
Both he and Knox made several spontaneous declarations throughout the original trial and first appeal. But only Knox actually testified. The spontaneous declarations are not under oath and are given from the lawyers' tables, not from the witness stand.
The court hearing Wednesday is also expected to address new DNA tests of the knife prosecutors say was used to kill Kercher. The knife was a critical piece of evidence in the original trial.
The tests involve a small portion of the knife. According to recent Italian media reports, the tests rule out the possibility that Kercher's DNA is present in the sample tested. That would support Knox and Sollecito's case.
The results are expected to be revealed in court Wednesday. The written conclusions by forensic experts have already been filed in Florence.
The Italian authorities who examined the spot on the knife are expected to present their report. They will then be questioned by all parties.
Knox isn't the only person watching the retrial from afar.
Citing health reasons, Kercher's relatives said in September that they had decided not to return to Italy for the retrial. The family said it would follow closely from Britain and remain in close contact with lawyers.