It doesn't take more than a few minutes after the man was shot dead to know whether he had a weapon. Frankly, it doesn't matter why the officer shot the man so long as he hadn't threatened the officer. In the time it took me to write this comment, a clear determination of whether the officer abused his power could have been made. If he did in fact have a weapon, you could bet your ass the police chief would have confirmed that.

What exactly do you think this investigation is going to yield? "It looked like he may have had a weapon" or "He made a threatening comment"? Neither are reasons why the officer should have shot the man.