Beating a police officer, trying to steal his gun and murder him, and then when that doesn't work, trying to beat him again, maybe kill him this time, well that does justify it.
But, when it comes to eye-witness accounts, when you have more than one, in this case several that corroborate the scenario related by the officer, I doubt that DNA evidence is going to dispute that. DNA evidence has been used to overturn convictions when you only have one witness or witnesses that didn't see what they thought they saw or lied. This happens quite often. It's still the best evidence there is. Ask any cop. Your problem is you're a liberal, and they spend most of their lives ignoring the truth.
More allegations without substance. No evidence of an attempt to "steal his gun". No evidence of any beating was found in the autopsy either. Then you descend into name calling because the facts are not on Wilson's side here.
FYI I do volunteer work with cops so I know their side of how these things go down. I have even used their shooting simulators so I probably have an even better idea of what was happening to Wilson than you do.
What we do know for certain is that Brown was unarmed and Wilson killed him. The investigation by the FBI won't only be relying on eye-witness testimony because they will be able to put together the forensics and come up with a finding that accounts for all of the facts.
Not every shooting by a cop is justifiable. This might be one of those instances. The questions that have arisen so far and the lack of answers from the FPD all point to having something to hide.