"You seem to be missing the concept of IDENTIFYING with CERTAINTY who someone is and what he has or has not done."
Unfortunately certainty is beyond human capability. Should this paralyze us with inaction? I don't think so.
"The example of killing someone who is in the process of assaulting someone is a strawman, because the killing is NOT for what he is suspected of having done, but rather for what he is VISIBLY doing in the present. "
Baloney. You can only suspect what he'll do. You can't know. I wonder how you came down on the Trayvon Martin case?