Judges at the retrial of Amanda Knox for the murder of a British student have ordered new DNA testing on the alleged murder weapon, a kitchen knife, on the first day of hearings.
The court in Florence on Monday also said it would re-hear the testimony of Luciano Aviello, a jailed mafia turncoat who at one point had accused his own brother of the grisly murder but then retracted.
Lawyers for the US student and her Italian former lover Raffaele Sollecito told the court the fresh tests were essential in clearing the defendants, as the victim's lawyer said the truth behind one of Italy's most notorious crimes was long overdue.
Knox and Sollecito spent four years behind bars for the murder of Meredith Kercher, who was found in a pool of blood in the house she shared with Knox in 2007, her body riddled with stab wounds.
An appeals court overturned their convictions in 2011 and Knox quickly returned to Seattle, but Italy's Supreme Court in March ordered a retrial following an appeal by prosecutors against what they slammed a "superficial ruling".
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"We need a key step forward on the DNA evidence ... We want the truth," Knox's lawyer Luciano Ghirga told the retrial's presiding judge Alessandro Nencini.
The knife, recovered from a kitchen drawer in Sollecito's house, bore tiny traces of Knox's DNA on the handle, and Meredith's DNA on the blade.
A third DNA trace had gone unexamined because it was seen as too low to produce conclusive results but the defence hopes it could help clear the pair.
