If you appear not to care about someone dying, does that make you guilty?

Cases like the Casey Anthony trial, or Diane Downs. The media is vicious in a sense where for example, Casey Anthony - they have no legitimate evidence tying her to her daughters alleged murder. That she must be guilty because of her lack of "typical" "normal" reactions. I disagree. That is subjective and not everyone reacts the way "emotional" people do. The fact that this seems to be a common theme in obvious cases where they have no substanstial evidence, is beyond me.

Yes Diane Downs is a murderer. But the fact that they really looked at her demeanor and tried to again use that as an indication of her guilt is awful and it proves massive idiocy.

The fact that Amanda Knox, they still have no evidence that legitimately ties her into the murder of her flatmate, but they simply run on her "reactions" and her "cold reaction" as a basis of evidence and that MUST make her the killer. Again. It's silly. I've noticed Americans seem to do this. Do these people in the court system not have anything better to grab onto?