Nothing is more confusing to a jury then when an expert admits on cross exam that the evidence she received from the cops and DA was less than optimal. Yet she still agrees with the DA. Beyond a reasonable doubt.

http://www.localsyr.com/story/d/story/forensic-blood-spatter-expert-takes-the-stand-in-n/83273/dsOb2Dn4WkmofRHzbOV-zg