THE RETRIAL of American Amanda Knox and her former ­Italian boyfriend for the 2007 murder of Meredith Kercher has opened in Florence but neither of the accused were in court.

Ms Knox and Raffaele Sollecito were convicted in 2009 of killing the 21-year-old British student in what was described as a drug-fuelled sexual assault.

After winning an appeal in 2011 that quashed the guilty verdict, both were freed from prison. But a new appeals process has begun after Italy's supreme court overturned the acquittals in March, citing "contradictions and inconsistencies".

Mr Sollecito's father Francesco said yesterday he was confident his son's innocence would be confirmed. "Deeper examination can only demonstrate what we already know, that is that Raffaele Sollecito has nothing to do with what that poor girl had to suffer," he said.

Ms Knox, 26, has always denied murdering Ms Kercher, whom she met when both were university exchange students in Perugia. She told US television this month that "common sense" told her not to return to Italy for the retrial, adding: "I was imprisoned as an innocent person and I just can't re-live that."

Ms Knox is not obliged to attend and can be represented by her lawyers, who said she was following the case closely from her home in Seattle.

If found guilty, she could appeal again to Italy's supreme court but if that failed, Italy could request her extradition.

Ms Knox served four years of a 26-year sentence, including three years on a slander conviction for falsely accusing a Perugia bar owner in the murder.

Mr Sollecito, 29, who has also always protested his innocence, plans to attend some of the hearings, his father said.

Ms Kercher was found with more than 40 wounds, including a deep gash in the throat, in the house she shared with Ms Knox in Perugia. Lawyers for Ms Kercher's family have welcomed the retrial, calling the previous ruling "superficial".

Ms Knox has said in recent ­interviews she wants to visit Ms Kercher's grave, but the Leeds University student's family said at the weekend the grave was ­Meredith's "safe place" and they hoped "that is respected by all".

Francesco Maresca, a lawyer for the Kercher family, said the supreme court's decision to throw out the acquittals reinforced signs of Ms Knox and Mr Sollecito's guilt. "We have always maintained they are guilty and that they were present at the crime scene," he said.

Referred to by the nickname Foxy Knoxy in many tabloid ­headlines, Ms Knox was initially portrayed as a sex-obsessed she-devil by prosecutors, but a lobbying campaign by her family helped modify perceptions.

In a memoir published this year, she painted herself as a naive young woman and a victim of Italy's snail-paced justice system, which drew heavy criticism for its handling of the case.

In explaining its decision to ­overturn the acquittal of Ms Knox and Mr Sollecito, the supreme court said the appeals court that freed them had not taken all the evidence into consideration.

It said the one person still in jail for the murder, Ivory Coast-born Rudy Guede, who is serving a 16-year sentence, was unlikely to have committed the crime alone.

Prosecutors said Ms Kercher was held down and stabbed after she resisted attempts by Ms Knox, Mr Sollecito and Guede to involve her in group sex. The supreme court said the theory of a sex game that spiralled out of control should be re-examined.

The prosecution's case was ­weakened in the last trial by ­forensic experts, who undermined the credibility of DNA and sharply ­criticised the initial response of police at the scene.