By Antonio Denti
ROME (Reuters) - Italy's highest court is expected to rule on Friday on whether to uphold the conviction of American Amanda Knox and her Italian ex-boyfriend for the murder of British student Meredith Kercher.The brutal killing and tangle of trials that followed gripped attention on both sides of the Atlantic, inspiring books and films. Kercher's family said Meredith, who died aged 21, risked being forgotten.
Almost eight years after the murder, the Court of Cassation's decision could trigger a new legal battle over whether to extradite Knox, 27. Her former boyfriend Raffaele Sollecito, 31, could also face decades in jail.
A verdict is expected at around 5.00 p.m. (1600 GMT).
Lawyers for the pair, who each served four years in prison before being acquitted on appeal in 2011 and then convicted for a second time after a retrial last year, argue the prosecution had presented a distorted picture from the evidence.
"If you take the Bible and divide it into many parts you can put together a pornographic book from the pieces," Sollecito's lawyer Giulia Bongiorno said as she arrived at court.
South London-born Kercher was found stabbed to death in a house she shared with Knox in the medieval hill town of Perugia in 2007. Rudy Guede, originally from the Ivory Coast, is serving a 16-year sentence for the crime, but judges ruled he did not act alone.
Knox, who returned to Seattle in 2011, and Sollecito have maintained their innocence throughout but Knox's lawyer Luciano Ghirga said on Friday his client was "very, very worried".
Following the 2011 acquittal, the Court of Cassation ordered a new trial. A Florence court convicted them again, saying the murder had been the result of a domestic argument, squashing the previous theory that it happened when a sex game went wrong.
If Knox's sentence of 28 years and three months is confirmed, Italy could ask the United States to extradite her. Legal experts are divided over whether Washington would have grounds to refuse the request, as it has done in the past in cases of military personnel convicted in Italy.
A U.S. rule against "double jeopardy" - or being tried again for the same crime after an acquittal - could stand in Knox's favour in the eyes of American court, as could the fact she was tried in absentia.
Prosecutors have asked for Sollecito, who has distanced himself from Knox during the process, to serve 24 years and nine months. His passport has already been confiscated.
(writing by Isla Binnie; editing by Ralph Boulton)