Amanda Knox has claimed in court that she had was hit by Italian police during questioning over Meredith Kercher's murder.
Knox, 21, stood up in the Perugia court and made the allegation despite police and official interpreters present during her questioning all denying the suggestion.
The American suspect's claim comes as Italian police officers who investigated Miss Kercher's murder continue giving evidence at the trial of Knox and co-defendant Raffaele Sollecito.
Knox told the court she had given the same version of events to police for several hours.
But, she added: "I was called a stupid liar. I received slaps to the head, I really did. I'm sorry, but it's true."
Reporting from Perugia, reporter Nick Pisa said: "Trembling and emotional, the American said that she was 'cuffed on the head' at a police station.
"She also said she was told to 'try to remember something else' before blaming the murder on an innocent bar owner, Patrick Lumumba."
Mr Lumumba is bringing a slander case against Knox after he was arrested, held and then released without charge.