As I get it, in the Jewish Law, the whole trial is based exclusively on interrogating the witnesses of all the details, but not a need for shreds of evidence or investigation of the crime scene.
Say the witnesses say the murder was under an apple tree, and provide all the details, but who's responsible to check whether there's an apple tree in this place at all?
Who's responsibility is to examine the body of the deceased? Did he die from the wounds or a heart attack? How one can be convicted without those details? That can be life-or-death facts.