The parents of American student Amanda Knox are being investigated for alleged defamation for saying Italian police abused their daughter before arresting her in the 2007 slaying of her British roommate.

Curt Knox told AP Television News on Saturday that he and his ex-wife, Edda Mellas, received notice of the investigation on Friday as they arrived in Italy for the final week of hearings in their daughter's case.

SLIDESHOW: Amanda Knox on Trial for Murder

He said he found the timing odd given that a verdict in the case is expected at the end of the week.

Italian news agency ANSA said Knox's parents were being investigated for alleged defamation stemming from an interview they gave Britain's Sunday Times in June 2008 in which the father alleged police had physically and verbally abused his daughter during questioning before she was arrested.

Police have denied harming Knox.

"We received some papers yesterday, it is true, we haven't see the file yet," Curt Knox said, declining to comment on the specific charges.

Both Curt Knox and Mellas said they thought the timing of the investigation was unusual.

"Well, it is odd that the timing is coming out now, five days before the end of the trial, and this is supposed to be something that happened over a year ago," Mellas said.

Knox, of Seattle, and Italian co-defendant Raffaele Sollecito are accused of murder and sexual violence in the 2007 death of Knox's roommate, Meredith Kercher, a university exchange student from Leeds.

Kercher's body was found in the apartment she shared with Knox in the central Italian city of Perugia on Nov. 2, 2007. Prosecutors believe the Briton was the victim of a drug-fueled sex game involving Knox, Sollecito and a third defendant, Rudy Hermann Guede of the Ivory Coast.

All three have denied wrongdoing.

Guede was convicted of the same charges in a fast-track trial last year and sentenced to 30 years in prison. He is appealing his conviction.

On Saturday, Sollecito's lawyers were giving their closing arguments in the case.

Prosecutors have requested life terms for Knox and Sollecito.