The decision by the Court of Cassation adds a further twist to a long-running case whose initial handling was sharply criticised by independent forensic experts.
Prosecutors accused Amanda Knox and her ex-boyfriend Raffaele Sollecito of assaulting and killing Kercher in 2007.
They were initially found guilty and sentenced to 26 and 25 years in prison respectively.
In 2011, their convictions were overturned and they were released after serving four years.
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Northwestern Scotland and Northern Ireland face a rain-hit weekend, while the rest of Britain enjoys some bright but generally dry weather.
All this week while reporting, I have been taking photos. They offer powerful portraits of the lives affected by the desperate outbreak.
Some of the world's biggest football clubs will ask FIFA to move the 2022 World Cup to spring.