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.
It took 6 months for a grand jury to exonerate another Wichita officer. http://www.texomashomepage.com/news/local-news/wichita-falls... The appeals etc took years after that. My point is, you don't let the cops make the determination about whether a cop is guilty. There are whole other layers of accountability.
Edit: and yeah I agree cops don't get convicted often enough. Either way a real investigation is going to take time.
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.