American Amanda Knox, who was exonerated by Italy's highest court of her roommate's brutal murder after multiple trials, is facing a new trial in Italy on a charge of slandering police.

Knox is charged with slander for testifying that her false accusation that a Congolese bar owner murdered her roommate was coerced. The false accusation led to Knox's conviction of slander of the Congolese man in the main murder trial, the only charge that stuck.

The police slander trial opened Tuesday. Knox is not expected to attend, but prosecution witnesses will be heard in September when the trial resumes.

Knox' defense lawyer Carlo Dalla Vedova said Wednesday he is "not worried" about the case, noting that the statute of limitations runs out in October 2016, requiring exhaustion of all appeals.