Italy's top court to rule on Knox conviction in Kercher murder

By Isla Binnie

ROME (Reuters) - Italy's highest court will decide on Wednesday whether to uphold former U.S. exchange student Amanda Knox's conviction for the 2007 murder of Briton Meredith Kercher, potentially sparking an extradition battle with the United States.

Knox, 27, and her former boyfriend, Italian Raffaele Sollecito, were convicted for the second time last year in the killing of 21 year-old student Kercher, who was found stabbed to death in a house the women shared in Perugia, central Italy.

Now the Court of Cassation must choose whether to confirm the conviction or order a retrial in a case for which Knox and Sollecito, who have both maintained their innocence throughout, have already served four years in jail.

The high-profile case has inspired books and at least two films, and Kercher's family said Meredith, the real victim, risked being forgotten.

Originally portrayed as a fast-living partygoer and initially convicted of murdering Kercher when a sex game went wrong, Knox came to be seen in much of her home country as a victim of a botched investigation and an unwieldy justice system.

The judges who passed the second guilty verdict, handing Knox a 28-1/2-year jail sentence and Sollecito 25 years, said the murder was the result of a domestic argument.

The Cassation Court is making a technical judgement on the validity of the last conviction, which the defence says is flawed. If the conviction is scrapped, the case will almost certainly go back to an appeals court for the third time.

If the conviction is confirmed, Sollecito, whose passport has been confiscated, could face a return to jail in his home country, and Italy may ask the United States to extradite Knox from her hometown of Seattle, where she has been since 2011, when the pair were acquitted on appeal and freed.

Knox, who did not attend last year's trial, has vowed to fight the conviction and said she would not willingly return to Italy.

Legal experts are split on the likely outcome if Italian authorities seek her return.

Some say a "double jeopardy" U.S. constitutional ban on retrial for the same offence after an acquittal would stand in Knox's favour, and that U.S. courts would frown on her having been tried in absentia.

Others argue the very existence of an extradition treaty implies that the United States accepts the Italian justice system, strengthening the case for extradition.

The U.S. State Department has said officials are monitoring the case.

Ivory Coast-born Rudy Guede is serving a 16-year jail sentence for the crime after a separate trial. Judges ruled he did not act alone.

(Reporting by Isla Binnie; editing by John Stonestreet)