prosecutors explained it's because the knife had been wiped clean. a forensic expert said finding dna but no blood mike it highly unlikely that the knife was used in a bleed murder. he also says it's surprising the prosecutor was even allowed to admit such a small unexplainable sample as evidence. >> would this have made it into a u.s. court? i don't think this would made it on to a u.s. lab report. >> reporter: what also made it into court was amanda's so-called confession. in a quirk of italian law the confession was thrown out of the criminal case against knox, but jurors heard it anyway as part of a civil case being tried simultaneously. in court, jurors heard magnini's evidence of guilt, and then when they went home each night, they heard news from a tabloid press gone wild. sensational headlines about the murder suspect dubbed foxy knoxy