Amanda Knox Expert Disputes Murder Weapon

PERUGIA, Italy, July 6, 2009— -- A medical examiner hired by Amanda Knox gave grisly testimony today about how her roommate was likely killed, and concluded that the knife presented by the prosecution could not be the murder weapon.

Medical examiner Carlo Torre also told the court he believed only one knife was used in the crime, and that only one person was involved in the killing.

Ivory Coast native Rudy Guede has already been convicted for taking part in the death of Knox's roommate Meredith Kercher and was sentenced to 30 years in prison.

Knox, 21, of Seattle, has been on trial in Perugia, Italy, since January, accused, along with her Italian former boyfriend Raffaele Sollecito, of sexually assaulting and murdering Kercher, a 21-year-old British exchange student with whom she shared a scenic cottage with a view of the Umbrian hills. Kercher was found semi-naked with her throat slit Nov. 2, 2007.

Torre, hired as a consultant by Knox's defense team, told the court today that the knife that investigators believe is the murder weapon -- a kitchen knife with a 12-inch blade found in Sollecito's kitchen -- was not compatible with some of the wounds found on Kercher. Investigators have said that Knox's DNA was found on the handle of the knife, and that traces of Kercher's DNA was found on the blade.

Torre used autopsy photos to illustrate his points and brought a styrofoam head on which he demonstrated the cuts to the victim's throat. Because of the graphic nature of the testimony, the judge decided that part of the hearing should take place behind closed doors.

Everyone except the legal teams and parents of the defendants were asked to leave the room. Knox's sister Deanna, 20, and her close friend, Madison Paxton, who were in court to support Knox along with her mother Edda Mellas, also had to leave. Ashley Knox, 14, Amanda's half-sister, is not allowed in court at all, because she is a minor.

Ashley told ABC News she was disappointed she couldn't be in court. "I was sad I couldn't see her for that extra time, but I know she'll do good," said Ashley.

Mellas told reporters that the images shown in court were not particularly gruesome, just close-up photographs of the wounds. Amanda Knox prefers not to look at them, and usually writes or doodles when they are shown, her mother said.

Torre, who is a renowned forensic consultant in Italy and has worked on a number of high-profile cases, told the judges and jurors today he believes the three cuts to Kercher's throat were made by a smaller knife, with a blade that was, at most, 3 inches long. He feels the the big wide slash to her throat was made by the sawing action of the smaller knife.