Italy's top court on Tuesday ordered a retrial of American Amanda Knox and a former boyfriend for the murder of British student Meredith Kercher, re-opening a case that prompted harsh criticism of the Italian justice system.
Kercher's body, with more than 40 wounds and a deep gash in the throat, was found in the apartment she shared with Knox in Perugia in 2007.
Prosecutors accused Knox and Raffaele Sollecito of killing the 21-year-old Leeds University student during a drug-fueled sexual assault.
The two were initially found guilty and sentenced to 26 and 25 years in prison respectively after a trial that grabbed world attention and drew stinging censure of the investigation by independent experts appointed to review evidence in the case.
In 2011, their convictions were quashed after forensic investigators challenged scientific evidence in the original trial. They were released after four years in prison and Knox returned home to the United States.
On Tuesday the Court of Cassation added a further twist by overturning the acquittal, accepting a request from prosecutors and Kercher family lawyers for a retrial, which will be held at a court in Florence.
"This is an important day for the Italian justice system," Kercher family lawyer Francesco Maresca said outside the court.
The case that led to the acquittals was "superficial" and "leaked from all sides," he said.
Knox said the decision was "painful." The prosecution had repeatedly been revealed as "unfounded and unfair," she said in a statement.
Her lawyer Luciano Ghirga said outside the court it was unclear if she would come back to Italy for the retrial.
Knox, dubbed "Foxy Knoxy" in many early media reports, was initially portrayed as promiscuous and dishonest but a lobbying campaign by her family helped change perceptions.
She returned to her Seattle-area home after she was released from prison in Italy and had been scheduled to speak publicly about the trial for the first time on American television in April, when her book of memoirs is also due to be released.
A third person, Ivorian Rudy Guede, was found guilty and sentenced to 16 years in a separate trial. He is now the only person serving time for the murder, although prosecutors say he could not have killed Kercher by himself.
"We are convinced there were more people in that room than Rudy Guede," Maresca said. "We are asking the judges to tell us something on this point, as long as their decision is well-grounded and thorough, not like the appeals court which was absolutely superficial."
Last year, prosecutors filed a motion to appeal against the acquittal, calling the verdicts "contradictory and illogical."
Italy's appeal court made the ruling on Tuesday after examining whether there were procedural irregularities which gave grounds for a retrial, rather than assessing the details of the case. Its reasons will be announced later.
Giulia Bongiorno, a lawyer for Sollecito, said the decision was not a guilty verdict for her client but just meant the court wanted a more in-depth examination of some aspects of the case.
"Unfortunately we have to continue the battle," she told reporters. "This is a sentence that says, with regards to the acquittal, that something more is needed," she said.
Additional reporting by James Mackenzie and Gavin Jones; editing by Barry Moody and Angus MacSwan.