The police took a knife from Raffaeles place and say it is the murder weapon (which many don't agree about, but anyway..:) They apparently found some DNA on even if it was an astronomically small amount. If Merediths DNA is on it would of course be interesting information - But how can it matter if the knife has Amanda's DNA on it? It was found in the kitchen drawer at her boyfriends place where she obviously was staying. If she has used his kitchen and touched his things doesn't make her a killer??
Another thing I am wondering about is IF they would be guilty, why in the world would they bring a murder weapon from his appartment? and back again? There are knifes in the house, why bring his?? And why bring it back? To risk being caught with a knife in your bag. And if R. would have been involved, why would he want the knife back. It all really doesn't make any sense at all.