Knox of Seattle, Washington, has been convicted of murdering and sexually assaulting British roommate Meredith Kercher and was sentenced to 26 years in prison. She denies wrongdoing and her appeals trial in under way in Perugia, a central Italian town.
The slander trial that opened Tuesday is a separate proceeding that stems from Knox's claims that she was beaten by police when questioned about Kercher's slaying in 2007. She maintains she was trying to defend herself and never meant to offend or slander anybody.
Knox has claimed she was beaten and put under pressure by police when she was questioned in the aftermath of Kercher's Nov. 1, 2007, slaying. She said police repeatedly called her a "stupid liar."
Police denied misconduct and filed charges saying Knox's comments were slanderous.
The trial involving the appeal of the murder conviction resumes Saturday.
Much of the trial hinges on a review of DNA evidence that is being carried out by independent forensic experts appointed by the court. The evidence was crucial in the first trial, where no clear motive emerged for the brutal killing.
The independent experts, originally scheduled to conclude their review and report to the court this month, are seeking more time.
Kercher's body was found in the apartment she shared with Knox when they were both foreign students in Perugia. Her throat was slit.