Also, how nimble do you have to be with either hand to put a gun up to someone’s head and pull the trigger? That’s a whole ‘nother can of worms compared to writing legibly.

It’s a question of shooting mechanics and where a left or right-handed shooter might keep his gun. I think the shot from the front seat is much more awkward, regardless of whether the shooter is left or right-handed. The right-handed shooter has to move the weapon across his body…it’s a bigger motion and makes it easier for Stine to notice. A left-handed shooter exposes his weapon to Stine (at least the right-handed shooter has his left hand to pin Stine against the driver’s door while he puts the gun to his head. The left-handed shooter has to turn his body to use his right hand in the same way. That’s a very awkward motion and it’s very slow. I don’t have a very strong opinion one way or the other whether Zodiac was in the front or back seat, but I think executing the shooting is much harder if the killer is in the front seat because Stine can more readily see what the killer is doing and when he reaches for his gun. The killer is much more likely to catch Stine completely by surprise if he is in the back seat.

I agree, and would add that besides the mechanics of the shot, Z in the front seat would give Paul a chance to see the attack coming and to wrestle defensively. If Z is in the back seat, Paul would be much less likely to see the gun drawn, but just as importantly, there is basically no way Paul could struggle with someone in the back seat while he’s driving.