In the third murder trial of U.S. student Amanda Knox and her former boyfriend, an appeals court in Florence began deliberations on Thursday, CBS News reported.

Closing four months of arguments in Knox's and Italian Raffaele Sollecito's third trial for the 2007 murder of her British roommate in the Italian university town of Perugia, Knox's defense team gave their last round of rebuttals.

According to CBS News, as the star defendant waited far away on a separate continent, Knox's lawyer Carlo Dalla Vedova told the court he was "serene" about the verdict because he believes the only conclusion from the files is "the innocence of Amanda Knox."

"It is not possible to convict a person because it is probable that she is guilty," Dalla Vedova said. "The penal code does not foresee probability. It foresees certainty."

The decision by the police of holding 26-year-old Knox overnight for questioning without representation and without advising her that she was a suspect in Meredith Kercher's murder was bought up by Dalla Vedova, CBS News reported.

The court would deliberate Thursday for at least seven hours, presiding Judge Alessandro Nencini said.

After being acquitted in 2011 in Kercher's murder, Knox spent several years in jail. Currently living in Seattle and awaiting the verdict, Knox wrote that she feared a wrongful conviction in an email to the court.

"Knox's absence does not formally hurt her case since she was freed by a court and defendants in Italy are not required to appear at their trials," CBS News reported. "However, Nencini reacted sternly to her emailed statement, noting that defendants have a right to be heard if they appear physically before the panel."

Always in a purple sweater, the color of the local Florentine football club, Sollecito has made frequent court appearances. He was in court again on Thursday, accompanied by his father and other relatives, CBS News reported.

Sollecito, who like Knox spent four years in jail, risks immediate arrest if convicted. "The situation for Knox remains complicated by her absence. In the case of a guilty verdict, experts have said it is unlikely Italy would seek her extradition until a verdict is finalized, a process that can take a year," CBS News reported.

Members of Kercher's family are expected to appear later at court.

According to CBS News, in a scathing dismissal of the appeals court acquittal, Italy's highest court ordered the third trial to examine the evidence and testimony that had been improperly omitted by the Perugia appeals court as well as to redress what it defined as lapses in logic.

"Most of all, the court was instructed to evaluate all of the evidence in their complexity," said Vieri Fabiani, one of the lawyers for the Kercher family.

"The first trial court found Knox and Sollecito guilty of murder and sexual assault based on DNA evidence, confused alibis and Knox's false accusation against a Congolese bar owner, which resulted in a slander verdict that has been upheld on final appeal. A Perugia appeals court dismantled the guilty verdict two years later, criticizing the 'building blocks' of the conviction, including DNA evidence now deemed unreliable by new experts, and the lack of motive," CBS News reported.

However, with the dismissal of the acquittal, the Florence deliberations will either confirm or overturn the initial guilty verdict, "as if the acquittal never happened," Fabiani said.

Within days of the discovery of Kercher's half-naked body on Nov. 2, 2007, in her bedroom in Perugia, Suspicion fell on Knox and Sollecito, according to CBS News.