You are so full of shit it isn't funny. The immediate circumstances dictate use of force in federal law enforcement. Babbitt was unarmed and climbing through a window. We can see Byrd's gun and hands in video, even if he, himself, isn't visible. He does NOTHING to try and get her attention or use less that lethal force.
He shoots her once, even though she poses no immediate threat to life or property.
Then, the most egregious part, he flees the scene. Explain that part away. What police officer shoots and kills a suspect then leaves the scene?
Byrd should have been charged with manslaughter and misuse of a firearm, leaving the scene of a shooting, along with violation of his own department's use of force rules.