I don’t know your mind but if you really came to such a conclusion without any preconceptions then you must need to get your eyes tested. What you think you saw simply doesn’t exist.
I hope either the State or the family bring a prosecution so a jury can decide culpability. I also hope that the family’s silence isn’t bought by the administration, or one of their billionaire backers, offering compensation. I want to see that ordered, not offered.
The best defence I can see is for the officer to blame a lack of training for an ill considered response, thus shifting the blame to where it really belongs. He might avoid jail that way, if accompanied by sufficient remorse.