Here is my theory: the officer keeps odd hours for work. He was unwisely investigating an abandoned car at 3 a.m. I wonder if he had called in his stop to any dispatch?
Calling backup in the form of a uniform and a black-and-white would be the intelligent thing to do. An honest armed citizen will NOT see that as a lethal threat. Quite the contrary, in fact.
The cop acted stupidly and recklessly, putting himself in a situation wherein a reasonable person would see him as a deadly threat.
Then he killed a citizen.
What do we call that, under the law?