The problem isn't necessarily that the officer had done wrong, so much as in the USA violence is almost always required. For instance, lets say the cop pulled this kid over; him being suicidal and all, pulls the glock out of the holster and shoots the officer then proceeds to kill himself. That may not have been what happened, but if I were a police officer in the USA I would definitely always be on alert, so maybe he used excessive force but for all we knew he could have thought that his life might have been or even was in danger.