It's more than that.
They put multiple holes in the victim, killing him, then ya got people saying the weapon was found in the victims holster...
This would indicate ya got people on that department that lack training, and or are trigger happy, paranoid, wanna be cowboys, or are just completely incompetent.
While I have no doubt your conclusions about the lack of training and the lack of professionalism of the officers in question, in my mind, it still comes down to a lack of leadership.
The senior officers are supposed to train the junior officers. They are the ones who are supposed to set the internal standards, train to those standards and hold their officers accountable to those standards. That is even truer when it comes to hiring and firing practices. Should an officer show an inability to adopt or support those standards the LEADERS are responsible for removing that officer.