Raffaele Sollecito, the former boyfriend of Amanda Knox, has been giving evidence in an Italian court at a retrial hearing in Florence.
The 29-year-old is attending the appeal trial, which sees the former lovers accused of killing the British student in Perugia in November 2007.
The trial is the latest in a drawn-out legal process that saw Knox, 26, and Sollecito convicted and jailed in Perugia in 2009, before being released after four years when they were cleared on appeal, only for that verdict to be overturned by Italy's supreme court this year.
While Knox has refused to travel from her home town of Seattle to appear in court for the new appeal, Sollecito has returned from a holiday in the Dominican Republic, an island with which Italy does not have an extradition treaty and which has hosted numerous Italian fugitives from justice.
Sollecito's father Francesco played down suspicions that his son was preparing to head back there after the hearing.
He said: "It was just a holiday - you can't be a fugitive for life."
He added that Raffaele Sollecito will now go back to his family home in Puglia, in southern Italy.
At the hearing, results will be revealed from a DNA test ordered by the judge on a knife found in Sollecito's apartment, which prosecutors believed to be the murder weapon.
Police originally claimed to have found both Miss Kercher's and Knox's DNA on the knife, but the Kercher DNA was challenged by a forensic evidence review during the appeal.
The latest trace to be analysed, which was considered too small to test during the review and is known as Trace "I", is likely to be Knox's DNA, results have shown.
Carlo dalla Vedova, a lawyer representing Knox, said: "The trace is a low copy number which the police say is not male, not Kercher, and could be Knox."
Mr Sollecito said: "The result means it was just a kitchen knife used by Knox in Raffaele's kitchen.
"The new trace is between the blade and the handle, the normal position for a finger when cutting bread.
"The DNA review has already excluded the possibility of Kercher's DNA being on the knife and the Supreme Court did not contest that, and now this new test shows again that there is no trace of Kercher on the knife."
Mr Dalla Vedova said that by showing the trace was not Miss Kercher's DNA, the test had bolstered Knox and Sollecito's defence.
"It's another element of the prosecution that falls down," he said.
However, apart from considering the knife, the court will also consider the Supreme Court's ruling that the appeal acquittal was full of "shortcomings, contradictions and inconsistencies".
After Wednesday's hearing, the trial will pick up again on November 25 for final arguments from the prosecution.
Dates will then be set for the final arguments from defence lawyers and rebuttals.
Francesco Sollecito confirmed his son has visited Miss Kercher's grave in the UK last year, apparently in defiance of the Kercher family who have asked for the grave to be kept private.
"It was before the Supreme Court ruling," he said. "Raffaele was in London and was taken by a friend whose idea it was."