If he hadn't freed himself.
Freed himself from WHAT? The only thing keeping him in the car was his hand on the seatbelt. Dubose's hands were in the air when the shot was fired.
And Tensing was not being dragged; during his "Stop.... STOP!" engagement his body actually moves FORWARD with respect to the window.
Observe:
Tensing lunges into the car: his foot is still on the ground
Tensing yells "stop" the first time. See the reflection on the car's side panel. Not only is he still on his own two feet, but he is far enough away that his body is not touching the side panel yet.
^ Tensing draws his gun. Dubose puts his hands up and Tensing is reaching for his seatbelt.
He is not holding on to anything that would physically keep him attached to the car.
^ Tensing grabs the seatbelt and leans FURTHER into the car, thrusting the gun towards Dubose's head. Note the angle of Tensing's arm; he is slightly IN FRONT of Dubose, pulling his seatbelt forward.
^ Half a second after the gunshot kills the driver, the car begins moving forward. Tensing starts to fall back and a moment later the rear frame of the window makes contact with his hand (it doesn't STRIKE his hand; the car is still moving too slowly for that).
There's one really obvious flaw with the "he shot in self defense" theory: Tensing reached into the car with his LEFT hand while drawing the gun with his right. If the car had been dragging him, his left arm would have been pulled to the back of that window and Tensing would no longer be able to place his right arm into the window to shoot Dubose in the head.
So it's really very simple. Tensing was NOT dragged by the car. Not thirty feet. Not thirty inches. He shot Dubose in the head and then threw himself backwards as the car began to move.
Go stick your arm and head into your friends car window and have them step on the gas. Then you'll see how armchair simplistic your notion is that him running along side the car and also being pulled along against his will are mutually exclusive. He had to run along side it at first or his arm and possible head would have gotten caught in there. It is clear cut that he shot only after the car had moved 5-10 feet forward. Whether he was technically "dragged" with limp legs for that distance or ran along as he tried to react to a danger created by the driver hitting the gas is a meaningless irrelevance.
Derec's frames, are far better at showing where the car was relative to other objects right before and during the shot. Note in the 3rd frame that Eddie presents, it is clear that the drivers seat isn't even parallel yet to the right-hand (from the officers view) sidewalk on that cross street and you can only see the right 20% of the SUV. By the Derec's second frame, the officer is not yet pointing his gun and yet that right hand sidewalk is already out of view and the driver's seat is already parallel with the SUV, which is now in full view. By the time the gun is fired, the drivers seat is now almost parallel with the row of bushes that were on the other side of the cross street from where the officer first reached into the car. IOW, the shot was only fired after the car had moved forward 5-10 feet (the width of that sidestreet).
Also, it is total nonsense that the driver ever "put his hands in the air" as though to surrender. His pulls his left arm up and away from the officer to avoid his grasp, but from the time the officer tries to open the door to the shooting 5 seconds later, the drivers right hand never leaves the wheel except to start the car at minute 2:44 which is when the cop yells "stop" and lunges in the window, and he puts that hand back on the wheel as he drives away, prior to the cop pointing his gun. By the time the cop shoots about 2 seconds after the driver and started the car and hit the gas, and after about 5-10 feet of movement. The cop shoots and immediately tumbles to the ground, showing the car was already going too fast for him to keep his balance (No, it is not possible for that gun to have recoil that would cause that). Yes, he was probably trying to run along side of it because his head and arm were in the car when it started to move and that would be the instinctual reflex as would holding onto the seatbelt.
At the point he asked the driver to stop (prior to pulling his gun) he had every reason to arrest him. He was trying to hide a bottle of booze at his feet, had no license, refused to cooperate, and was trying to flee the scene. The cops mistake was trying to stop him by lunging into the window, but once he did that, the driver put the cop at serious risk by hitting the gas. The cop was in danger when he fired. He had to let go and push himself free of the car hoping the now moving window jam didn't catch his neck or that he didn't fall under the back tires. That takes more calm and repression of the instinct to grab the driver than anyone criticizing this cop likely has.
That said, he probably should not have pulled the gun to try and stop him or reached in to put himself at risk when the driver drove off. These, combined with this criminals criminal actions to try and flee, set up the situation within which the officer fired possibly out of self-preserving panic or possibly to stop a fleeing criminal who at that point was under reasonable suspicion for much more than what he was pulled over for. At worst, its reckless manslaughter. I think its likely that he initially held on as a reflex, but knew he couldn't hold on anymore, so he fired then pushed himself away from the moving car. IOW, he fired to stop a fleeing suspect. Unless the suspicion was for a violent crime, then lethal force is illegal and criminal but still well short of murder. But its nonsense to claim he was only a suspect for a missing plate. He was a DUI suspect, and his refusal to show ID combined with his clear act of fleeing means he was likely on the run from or currently committing a more serious crime.
BTW, if we are going to allow DUI that results in deaths to be prosecuted as homicide (which is currently the case), then isn't a DUI suspect that attempts to drive off engaging in attempted homicide? What level of force should we allow cops to use to stop a suspect that is fleeing with a deadly weapon where there is clear intent to use it, and how should that apply to a DUI suspect driving off, who if drunk, essentially is in the act of using a deadly weapon like a guy firing a gun into the air (which can kill people randomly)? This is a more general issue about principles of law, so I'll start a new thread about it, but its worth noting there was a basis to suspect that at minimum this guy was trying to speed off while under suspicion of DUI.
