Amanda Knox Case Turns on Sharply Disputed Forensics

ROME Nov. 19, 2009— -- When summations begin Friday in the trial accusing Amanda Knox of murdering her British roommate, prosecutors and defense attorneys will have the testimony of 130 witnesses and experts over the past eight months to highlight in order to prove the guilt or innocence of the Seattle exchange student.

The case is built on forensic evidence which is being sharply contested, and a mountain of circumstantial evidence.

It is lacking, however, a witness who can put Knox and her co-defendant and former boyfriend Raffaele Sollecito at the scene of the crime - the cottage in Perugia, Italy, when Meredith Kercher was slain on Nov. 1, 2007. (A third person, Ivory Coast native Rudy Guede, has already been convicted of taking part in the murder.)

What the prosecution claims is the murder weapon is also being sharply contested.

And there is a question of motive. Prosecutors state that Kercher died in the course of a sexual encounter that went bad when Kercher refused to participate.

Knox is a sweet-faced Seattle, Wash., student who was 20 at the time of the homicide, hardly the profile of a grisly murderer.

But her good looks have helped attract often lurid coverage of the case by the Italian and international media which has eagerly followed her statements, court demeanor, and trial tactics. It is unclear whether that could have an effect on the jury's deliberations in Italy where juries are not isolated.

When prosecutor Giuliano Mignini addresses the jury, he will argue that the case is a "puzzle" in which all the elements come together to prove their guilt. He will attempt to put that puzzle together for the jury, while Knox's lawyers will try to show that the puzzle pieces don't fit.

What will be challenged most in the courtroom will be over the forensic evidence.

The most incriminating items, if they hold up in the minds of the six jurors and two judges, are a kitchen knife from Sollecito's home and Kercher's bra clasp.

Investigators identified Kercher's DNA on the blade and Knox's DNA on the handle of the 6.5 inch long knife. The prosecution claims this is the murder weapon and the DNA proves that Knox is the one who wielded it.