The retrial of American Amanda Knox and her former boyfriend begins Monday in Florence, Italy, in the killing of British student Meredith Kercher in 2007.

Earlier this year, Italy's highest court overturned their acquittals and ordered another trial.

Knox, now a 26-year-old University of Washington student in Seattle, has not returned to Italy for the trial, nor is she compelled by law to be there. The appellate court hearing the new case could declare her in contempt of court, but that carries no additional penalties.

"Facts are facts, and I'm not afraid of them," Knox told ABC News, but she will remain in the U.S. for the proceedings.

In 2009, Knox and Raffaele Sollecito, now 29, were found guilty of the murder of her 21-year-old roommate. They were sentenced to more than 20 years in prison by a court in Perugia, Italy. The couple was acquitted on appeal in 2011.

Then, in March, Italy's highest court overturned that acquittal, saying the prosecution's evidence hadn't been properly considered by the court. A new trial was ordered.

Knox, who spent four years in a Perugia prison, insists she's innocent. She says her presence at the retrial would only cause a repeat of the media circus of her first two trials, something she wants to avoid.

'Facts are facts, and I'm not afraid of them.' - Amanda Knox

"'We refute the idea that because Amanda is not coming that Amanda is guilty, that Amanda is using a strategy. Amanda always said she was a friend of Meredith's, Amanda has always respected the Italian justice system," Knox's defence lawyer Luciano Ghirga told reporters before the trial opened.

Sollecito, an Italian who has been living in the Caribbean, says he will attend.
If Knox is found guilty, Italy could try to extradite her from the U.S. to serve a jail term.

Perugia bar owner Patrick Lumumba showed up at the trial Monday, saying he did so to underline the damage he suffered from Knox's false accusations. Three of the years Knox served in prison were for a slander conviction, for falsely accusing Lumumba in the murder.

Kercher's body was found in November 2007 in her bedroom of the house she shared with Knox in Perugia, a central Italian town popular with foreign exchange students. Her throat had been slashed. Suspicion fell on Knox and Sollecito, who had been dating for less than a week, due to their conflicting stories and what some viewed as strange behavior by Knox. 

A third man, Rudy Guede, was convicted in the slaying and is serving a 16-year term.

'Infinite trial'

On Monday, another of Knox's lawyers, Carlo Dalla Vedova, warned of a risk of an "infinite trial," since the charge of murder has no statute of limitations. Sollecito's lawyer, Giulia Bongiorno, asked the court to accept only "reliable evidence," saying the intense media attention on the case had tainted witness testimony during the previous trials.

The Florence court agreed to only three requests, a sign that it will apply its own interpretation to reams of evidence and testimony already submitted in the previous lower court conviction and appellate court acquittal.

Besides a new DNA test on the knife found in Sollecito's kitchen, the court also agreed to the prosecution's request to again hear testimony from a jailed mobster, Luciano Aviello, who had accused his brother in the murder in a jailhouse discussion with Sollecito. Aviello, whose criminal convictions include defamation, is to testify Friday.

The court also accepted into evidence defence photos showing Sollecito's fingernails bitten down at the time of his arrest, which the defense argues is proof he didn't participate in what prosecutors allege was a drug-fuelled sex game that turned murderous.

Knox's protracted legal battle in Italy has made her a cause celebre in the United States and has put the Italian justice system under scrutiny.  The Italian system does not include U.S.-style protection against a defendant being put in double jeopardy by government prosecution. Knox's absence was noted by the court Monday.

With files from The Associated Press