Rome - American Amanda Knox and her former Italian boyfriend face their fourth verdict in six years for the murder and sexual assault of a British student brutally killed in the Italian city of Perugia in 2007.
Knox has been in the United States ever since an appeal court acquitted her and lover Raffaele Sollecito in 2011 of the murder of Meredith Kercher, who was found partially naked in a pool of blood in the house she shared with Knox.
She has not returned to Italy because says she fears being "wrongly convicted".
The pair's acquittals were overturned by the supreme court in 2013, which accused the appeal judge who freed them of "a rare mix of violation of the law and illogicality" and criticised the approach taken to DNA evidence and witnesses.
The case was sent to a retrial in Florence, where a verdict is expected on Thursday.
With little change in the case details over the years, it is not clear how presiding judge Alessandro Nencini will rule.
Knox told the Florence court in an email that she was "not a monster" but would not be coming to Italy for the trial or verdict because she was "afraid that the vehemence of my accusers will leave an impression on you".
Whatever the outcome, an appeal by either side will send the case back before the supreme court again before the verdict is considered final.
Experts say it is unlikely that Knox could ever be extradited even if she is definitively convicted, but she has said she fears "becoming a fugitive" from Italian justice.
A guilty verdict now could see Sollecito back behind bars or stripped of his passport to prevent him fleeing the country while the appeal process is exhausted.
Last week, an American woman claimed the 29-year-old had asked her to marry him in order to secure a Green Card, having first proposed unsuccessfully to Knox. Sollecito's lawyers said on Tuesday that they were considering suing the woman.
Local drug dealer Rudy Guede, whose DNA was found at the scene, is the only person currently serving time for the murder, but investigators say the knife wounds found on the Leeds student's body suggest there was more than one killer, a theory supported by the supreme court.
Kercher was found with her throat slit and had suffered a "slow, agonising death", according to a coroner's report.
Forensic tests determined that she had been sexually assaulted, possibly even while she was being stabbed.
The Florence court has focused largely on the presumed murder weapon, ordering fresh DNA tests on a kitchen knife found in Sollecito's apartment.
A previously untested sample of DNA was shown to belong to Knox, but a tiny sample on the blade which the original forensic tests said belonged to Kercher was too small to retest and is considered inconclusive by the defence.
Prosecutors claim Knox's DNA on the knife and Sollecito's DNA on a bra clasp ripped off during the attack prove they stabbed Kercher while Guede raped her.
Concrete proof has proven elusive, particularly after police video of the crime scene revealed sloppy practice by officers which likely contaminated evidence.
The prosecution say Knox removed traces of herself and Sollecito from the crime scene, a theory ridiculed by the defence, which insists she could not have cleaned up some DNA traces while leaving those incriminating Guede.
Prosecutors say Knox's original statement to police, in which she falsely accused Congolese bar owner Patrick Lumumba of the murder is evidence she was trying to cover something up.
Kercher's siblings are expected to attend court on Thursday for the verdict. Sollecito's father has said his son is likely to remain at home to avoid the media scrum, while Knox will wait for the news in her home town of Seattle.
"If Amanda Knox is innocent as she claims, she should come to the court for the verdict. I think she's running away", Lumumba said.