important point is cops can shoot to wound OR shoot to kill.
civillians just shoot to stop the threat. whether the criminal’s wounded or dead isn’t a decision a civillian makes beforehand, either one is just the consequence of atopping the threat.
as a civillian you never shoot to wound or do a warning shot. in either case, if you can do either one of them, you don’t need to shoot at all.
I had a training once, and the trainer, an ex-cop, minced no words. Here is the "Coke bottle," and that's where you shoot. Nowhere else. Missed the bottle, failed the exercise. (This is an outline on a human target that surrounds vital organs. You can see examples here.)
He explained that even a mortally wounded man, a dead man walking, can still kill you if he can reach you. Hence the 21-feet rule. It only takes a few seconds for an attacker to cross that distance (go out and measure 21 feet! It's about 1.5 car lengths!) but you need about 2 seconds to release the retention latch, draw, and fire. You may have to fire as soon as the gun clears the holster and is rotated toward the target. You have no time to aim for extremities, and you can't take the risk of missing. If the threat is not severe enough to shoot to kill, don't touch the firearm.
And here we see another rookie mistake of GZ: he failed to maintain situational awareness and allowed an attacker to approach within strike distance.