If I were on the jury, of course I'd have to see all the evidence to make a decision in good conscience. If I am just posting an opinion and playing armchair quarterback, though, I'd vote for manslaughter.
I don't think GZ started out with the intention to shoot anyone. I doubt (though I don't know for sure) that when he actually shot TM, he was "happy" about or completely indifferent to the harm he was causing.
At the same time, he had no right to go chasing off after someone, toting a gun no less, and especially no right to try to detain someone. He had no business getting out of his vehicle, and he should have been able to figure out that harm could ensue from his actions. :twocents:
I admit I could be totally wrong and I'm not a lawyer, so maybe "depraved indifference" could include more than I think.