It is sad this happened. I generally support Police Officers...this one is pretty damning though. 8 shots in the back as the suspect (unarmed) is running away. To me, it's seems to be a clear case of excessive force for the situation.
There is another thread here in which it shows an officer arriving at the scene where a family (crazy mom) drives off. His first reaction is to draw his gun and start firing at the car, without really knowing the situation. Had he struck one of the family members, he would likely be in a LOT more trouble, in my opinion.
It's tough to be a police officer. Still, you need to know when NOT to draw and fire your weapon with deadly force. Both officers in these situations crossed that line, in my opinion.