Story highlights Amanda Knox's attorney says appeal is certain, too soon to talk of extradition

Italian court finds Amanda Knox, ex-boyfriend guilty of murder in retrial

Knox says the legal proceedings have gotten out of hand, are perverted

Both were convicted previously of British student's murder, later acquitted on appeal

An Italian appeals court convicted former exchange student Amanda Knox and her ex-boyfriend Raffaele Sollecito on murder charges Thursday night.

Prosecutors said the couple had killed Meredith Kercher in November 2007. They were convicted two years later of murder, but those charges were overturned on appeal in 2011.

A judge said Thursday that Knox, also convicted of slander, was sentenced in absentia to 28 1/2 years in prison. Sollecito's sentence was 25 years.

Knox, who was at home in Seattle, Washington, said her conviction would bring no consolation to the Kercher family.

"I am frightened and saddened by this unjust verdict," she said in written remarks. "Having been found innocent before, I expected better from the Italian justice system. The evidence and accusatory theory do not justify a verdict of guilt beyond a reasonable doubt. ...There has always been a marked lack of evidence."

She called the legal proceedings a travesty.

"This has gotten out of hand. Most troubling is that it was entirely preventable," she said. "I beseech those with the knowledge and authority to address and remediate the problems that worked to pervert the course of justice and waste the valuable resources of the system."

Knox also said that Kercher's family had suffered greatly.

"Their grief over Meredith's terrible murder will follow them forever. They deserve respect and support."

What comes next

Presiding Judge Alessandro Nencini has 90 days to write his arguments behind the jury's ruling. Once that is out, lawyers have 90 days to appeal.

Knox's attorney, Ted Simon, said there will certainly be an appeal and cautioned that extradition shouldn't yet be a part of the conversation surrounding the case.

"It's really not in play right now, because first of all, she has another appeal to the Supreme Court of Italy," he told CNN's Anderson Cooper 360. "In Italy, under their system, you're still actually presumed innocent until that third, final stage."

Simon said that if extradition does become an issue, Knox has "very substantial defenses" that can be used.

"But I think we shouldn't get ahead of ourselves," he told CNN. "The bottom line is, there is no evidence. There was no evidence, and there never will be any evidence, and that's why this is such a gross miscarriage of justice."

Legal analysts debated whether the U.S. would send Knox back to Italy if Rome requests extradition.

It is unlikely that Knox will return to Italy to serve additional prison time because U.S. law dictates that a person cannot be tried twice on the same charge, a legal expert told CNN.

"She was once put in jeopardy and later acquitted," said Sean Casey, a former prosecutor who is now a partner at Kobre & Kim in New York. "Under the treaty (between the two nations), extradition should not be granted."

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Photos: The Knox-Sollecito retrial Photos: The Knox-Sollecito retrial Amanda Knox at her parents' home in Seattle, Washington, on March 27, 2015. Knox and Raffaele Sollecito (not pictured) were acquitted by Italy's highest court in the murder of British student Meredith Kercher. Hide Caption 1 of 14 Photos: The Knox-Sollecito retrial Amanda Knox appears on NBC's "Today" show. Knox spent four years in jail because of murder charges in the death of her roommate Meredith Kercher while studying abroad in Perugia, Italy. Hide Caption 2 of 14 Photos: The Knox-Sollecito retrial Appeals Court Judge Alessandro Nencini, center, reads the verdict in the death of British student Meredith Kercher in Florence, Italy, on Thursday, January 30, 2014. The appeals court upheld the convictions of Knox and her ex-boyfriend Raffaele Sollecito for the 2007 murder of her British roommate. Knox was sentenced to 28½ years in prison, raising the specter of a long legal battle over her extradition. Sollecito's sentence was 25 years. Hide Caption 3 of 14 Photos: The Knox-Sollecito retrial Sollecito, left, and his father, Francesco, leave after attending the final hearing before the verdict on January 30. After nearly 12 hours of deliberation, the court reinstated the guilty verdict first handed down against Knox and Sollecito in 2009. Hide Caption 4 of 14 Photos: The Knox-Sollecito retrial Patrick Lumumba, the Congolese bartender Knox originally accused of Kercher's murder, talks to the press outside the courthouse during a break form the appeal trial of Knox and Sollecito on September 30. Hide Caption 5 of 14 Photos: The Knox-Sollecito retrial Knox and her former boyfriend Sollecito were convicted in 2009 to 25 years in prison (Sollecito got 26 years). The conviction was overturned in 2011 for "lack of evidence." But Italy's Supreme Court decided last year to retry the case, saying the jury that acquitted them didn't consider all the evidence and that discrepancies in testimony needed to be answered. Hide Caption 6 of 14 Photos: The Knox-Sollecito retrial Meredith Kercher, a 21-year-old British exchange student, was found dead with her throat slit in an apartment she shared with Knox in Perugia, Italy, on November 2, 2007. Hide Caption 7 of 14 Photos: The Knox-Sollecito retrial When Knox was detained for questioning in 2007, she implicated Lumumba, the owner of a bar where Knox worked. Lumumba was taken into custody and released after two weeks in prison when his alibi was corroborated. He later won a libel suit against Knox. Hide Caption 8 of 14 Photos: The Knox-Sollecito retrial Sollecito , Knox's boyfriend at the time of the murder, was convicted in December 2009 with Knox and released when their cases were overturned. Prosecutors testified that police scientists found Sollecito's genetic material on a bra clasp of Kercher's found in her room, while his defense claimed there wasn't enough DNA for a positive ID. Hide Caption 9 of 14 Photos: The Knox-Sollecito retrial Rudy Hermann Guede, an Ivory Coast native raised in Perugia, was convicted separately from Knox and Sollecito and is now serving 16 years. Guede admitted to being with Kercher on the night she died, but said he didn't kill her. Both Knox and Sollecito argued that he was the killer, and Guede suggested the couple took Kercher's life. Hide Caption 10 of 14 Photos: The Knox-Sollecito retrial Meredith Kercher's family lawyer Francesco Maresca, left, argued in court in 2011 that the multiple stab wounds implied more than one aggressor killed Kercher. Pictured from left are Maresca, Kercher's father John, sister Stephanie, brother Lyle and brother John at a press conference in 2008. Hide Caption 11 of 14 Photos: The Knox-Sollecito retrial Carlo Dalla Vedova, one lawyer on Knox's defense team, argued in court that "the only possible decision to take is that of absolving Amanda Knox" in his closing argument for her appeal hearing. Hide Caption 12 of 14 Photos: The Knox-Sollecito retrial Carlo Pacelli represented Patrick Lumumba in his civil suit case. He called Knox two-faced and a "she-devil." Hide Caption 13 of 14 Photos: The Knox-Sollecito retrial Giulia Bongiorno, the lead lawyer on Raffaele Sollecito's defense team, compared Knox to Jessica Rabbit on the movie "Who Framed Roger Rabbit?" Knox is not bad, just "drawn that way," Bongiorno said in her closing statements in the 2011 trial. Hide Caption 14 of 14

CNN legal analyst Mark O'Mara said that the United States has to respect the treaty.

"We have to follow the letter of the law," he said Thursday.

Knox says she won't go back

Kercher, 21, of Great Britain, was found partially nude in a pool of blood in the house she shared with Knox in the picturesque town of Perugia, where both women were exchange students.

Knox has said she is afraid to return to Italy, where she spent four years behind bars.

"I will become ... a fugitive," she told Italian daily La Repubblica this month, when asked what she would do if she was found guilty in the second trial.

Italy's Supreme Court in March overturned the pair's acquittals, saying that the jury did not consider all the evidence and that discrepancies in testimony needed to be answered.

The case was sent to a retrial in Florence.

Ruling unclear

The retrial began in September, refocusing international attention on the case that grabbed headlines in Italy, Britain and the United States -- but neither Knox nor Sollecito were present in court.

Both Knox and Sollecito have maintained their innocence.

'Fugitive'

Knox, 26, and Sollecito, 29, were convicted in 2009 of killing Kercher, who was found with more than 40 stab wounds and a deep gash in her throat.

Speaking on Thursday, Knox's defense team asked for an acquittal.

Knox has always denied murdering Kercher and has maintained she is not guilty in a written statement to the Florence court.

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"I must repeat to you. I'm innocent. I did not rape, I did not steal ... I did not kill Meredith," Knox said in a lengthy e-mail presented by her lawyer to the court in December.

Sollecito was in the Dominican Republic at the start of the retrial but returned to Italy.

In November, he took to the stand to make a spontaneous declaration, saying the charges against him were "absurd."

"For me, it's a nightmare that goes beyond imagination," he said of what he's been through.

'No one remembers Meredith'

"They are tired of this long trial and they want justice," Francesci Maresca, attorney for the Kercher family, said.

The Kercher family welcomed the retrial ruling, Maresca said in March, adding they believed the ruling that acquitted Knox and Sollecito was "superficial and unbalanced."

They believe more than one person was in the room when Kercher was killed, he said.

"No one remembers Meredith, while the two defendants write books, speak to the media and earn money," Maresca told the court in closing remarks last month.