Final answer:
Six weeks after finding the knife, police discovered a bra clasp with DNA evidence at the Amanda Knox crime scene, which was used in the trial.
Step-by-step explanation:
In the Amanda Knox trials, six weeks after finding the knife with Meredith’s DNA on it, the police discovered D. A bra clasp with DNA evidence. This bra clasp was said to have DNA from Raffaele Sollecito, Knox’s friend at the time. The DNA evidence on this bra clasp became one of the contentious pieces of evidence used in the trial, as the defense argued that the DNA could have been the result of contamination due to the lapse in time between the murder and the discovery, as well as the way it was collected and handled.