Meredith Kercher was found dead two months into her studies in Italy
Key forensic evidence in the case of a British student killed in Italy was wrongly linked to one of the defendants, a forensic expert has said.
A bloody footprint at the crime scene was attributed to Italian Raffaele Sollecito, but Francesco Vinci has told a court the print was the wrong size.
Mr Sollecito is accused with American Amanda Knox of the murder of Meredith Kercher in Perugia in 2007.
The former couple deny killing the 21-year-old exchange student from London.
In his testimony on Friday, Mr Vinci compared pictures of a footprint on a bathroom rug at the house where Ms Kercher was found with images of Mr Sollecito's feet.
The expert witness for the defence told court that the sizes and shapes "absolutely don't match".
Ms Kercher, who was studying at Leeds University, was found with her throat cut in a Perugia house she and Ms Knox shared.
Prosecutors say she was killed during what had begun as a sex game.
A third person, Rudy Guede, has been jailed for 30 years for the killing. He has denied wrongdoing and is appealing against his conviction.
The trial continues.