Even if Brown did commit robbery...

[jberryhill]

89. This is your OP:

"what's to say he was beating the policeman who shot him? Just the policeman's word?"

Answers to those questions are:

1. If an examination of Mr. Brown's body indicated fresh offensive wounds, it would be evidence of him having recently hit someone.

2. If an examination of Mr. Brown's body indicated absence of offensive wounds, one would have to ask a medical examiner whether that meant he did not hit someone.

I am not a medical examiner. Finding "something" may be indicative of "something". Finding "nothing" may or may not be indicative of "something" or "nothing".

Your question was directed to whether there could be any evidence of him "beating the policeman". Yes, there can be evidence of having beat someone, and how long ago one may have beat someone.

It is also important to understand what the word "evidence" means, as distinguished from what the word "proof" means, since people tend to confuse the use of those two words.

As to "Is it possible to hit someone and not sustain an injury?" I have no earthly idea. Many things are "possible". As a proposition, I would believe, absent further education on the point, that if one person was to hit another person without a weapon in a manner sufficient to inflict injury, then it seems likely one would have a corresponding injury of some kind.

Physics doesn't care if you slam your face into my fist, or whether I slam my fist into your face. Either way, it is a collision between bones wrapped in skin.

Various kinds of physical confrontations are reconstructed or rendered more or less likely from physical evidence all of the time, and some wounds can be characterized as defensive (such as stab wounds on the palms of a person trying to avoid being stabbed) or offensive (such as bruising to the knuckles of someone who has punched someone else).

It may also be that the evidence is indeterminate. If your skin is found under my fingernails, I may have been trying to restrain you, or I may have been trying to scratch you.