Amanda Knox arrives at court during her appeal trial in 2011. Agence France-Presse/Getty Images
FLORENCE—An Italian appeals court Thursday found Seattle native Amanda Knox and her Italian former boyfriend guilty of murdering a British student in 2007, the latest twist in a long legal saga that has riveted the media's attention and divided public opinion on both sides of the Atlantic.
After more than 11 hours of deliberations, an eight-person panel of judges and jury members in an appeals court in Florence found Ms. Knox and Raffaele Sollecito guilty of murder and sexual assault.
British student Meredith Kercher was found dead in her apartment in the central Italian town of Perugia in 2007, and police subsequently arrested Ms. Knox, her then-boyfriend Mr. Sollecito and other suspects.
Amanda Knox and Raffaele Sollecito were found guilty of murder by an Italian court on Thursday. The case has been bouncing back and forth through Italy's legal system since 2007. Why did it take so long to reach a verdict? And what happens now? Image: Getty Images
The ruling, however, isn't likely to bring an end to the case, as Italian law allows both sides to appeal. After the verdict was read, the defendants' lawyers said they plan to appeal. Ms. Knox and Mr. Sollecito have both maintained their innocence.
"I am frightened and saddened by this unjust verdict," said Ms. Knox in a statement. "The evidence and accusatory theory do not justify a verdict of guilt beyond a reasonable doubt. Rather, nothing has changed. There has always been a marked lack of evidence."
"It's a painful development, but it's simply one development," said Giulia Bongiorno, who represented Mr. Sollecito.
Ms. Kercher's brother Lyle was present with their sister Stephanie for the verdict. The ruling "was the best we could have hoped for," he told reporters. "No matter what the verdict is there will never be a case for celebrating anything."

Background on the Case

U.S. student Amanda Knox, her Italian former boyfriend Raffaele Sollecito and the trial for the 2007 murder and sexual assault of U.K. student Meredith Kercher.
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The mystery surrounding Ms. Kercher's death and the subsequent trial have electrified public opinion since Ms. Kercher was found dead in an apartment she shared with Ms. Knox in Perugia, a university town in central Italy where both were exchange students. The 21-year-old had been stabbed multiple times and her throat had been slashed, with her body also showing signs of sexual assault, according to the prosecution.
The following year, a court convicted Rudy Hermann Guede, an Ivory Coast national who had briefly known Ms. Kercher, for her murder, sentencing him to 16 years in prison. The ruling suggested he didn't act alone, though other possible suspects who might have taken part in the murder weren't identified.
Mr. Guede, whose DNA was found on the body, said he was in the apartment but denied killing Ms. Kercher, saying he had been framed by Ms. Knox and Mr. Sollecito.
In 2009, Ms. Knox and Mr. Sollecito were convicted of murder and sexual assault. But an appeals court overturned the ruling in 2011. Ms. Knox was freed from prison, where she had spent four years, and returned to Seattle.
Then, in a surprise decision last year, Italy's Supreme Court ordered a retrial, arguing that the reasoning behind the 2011 reversal had been "contradictory." A new trial began in an appeals court in Florence in September.
Ms. Knox, now 26, declined to attend the retrial in Florence, saying she was afraid she wouldn't get a fair trial. Neither she nor Mr. Sollecito, 29, was obliged to attend, but Mr. Sollecito made a few appearances in court. He wasn't present for the verdict, and Italian authorities will take away his passport in the coming days.
On Thursday, the judges handed down a sentence of 25 years in prison for Mr. Sollecito and 28 for Ms. Knox. Ms. Knox's sentence was two years longer than her 2009 sentence, although the judges didn't immediately explain that decision.
Seven years of twists in the case have raised questions about the credibility of Italy's justice system. Some critics in the U.S. blasted the handling of the case as ham-handed and highlighted the multiple appeals and the retrial as emblematic of an intractable and unfair system. The Italian government hasn't commented on the trial, but it has sought to overhaul the system in recent years.
During this retrial, the defense returned to questions about the reliability of forensic evidence that had been raised during the first trial. Back then, experts argued that DNA evidence found on a knife—the alleged murder weapon—was insufficient to link it to Ms. Knox.
Prosecutors instead argued the murder stemmed from an argument between the roommates about cleanliness in the apartment, dropping allegations used in the previous trials that the killing was the result of a sex game gone wrong.
If Ms. Knox wins her next appeal, which will take months to hear, prosecutors can in turn appeal that verdict. But if the American student loses all appeals, Italy could seek her extradition.
It is unclear whether the U.S. would agree to send Ms. Knox back to Italy. In light of the multiple appeals and trials in Italy, a U.S. judge may invoke the principle of double jeopardy, whereby a suspect can't be tried twice for the same crime, say experts.
Instead, Italian law doesn't consider a conviction final until the appeals process has been exhausted regardless of the number of times a defendant has been put on trial.
In an interview with Italian daily la Repubblica earlier this month, Ms. Knox said she would resist extradition if the appeals end in a guilty verdict. "In that case, I will be…a fugitive," she said.
—Joel Millman contributed to this article
Write to Gilles Castonguay at gilles.castonguay@wsj.com