It should be noted that the pharmacist would have had no way of determining the condition of the downed bad guy under these circumstances. The second attacker posed too great of a threat to pause to evaluate the condition of the downed attacker.
If you shoot a perp, he falls to the ground and is not moving, and you shoot him 5 more times, you'll likely have a hard time convincing a DA that those 5 additional shots were justified.
Furthermore, if you watch the surveillance video, he had more than enough time to determine the condition of the downed bad guy.
1) Perps come in store.
2) Victim shoots, perp 1 falls down, perp 2 flees store.
3) Victim walks past perp1 to door, turning his back to perp 1.
4) Victim goes out door, to parking lot.
5) Victim comes back in store, walks directly past perp 1, turns his back to perp 1 as he calmly walks to the back of the store.
6) Victim walks to the front of the store, stands over perp 1, and fires 5 times.
If the victim really felt that perp1 was still a threat, why did he turn his back to him at step 3? Why did he walk past perp1 and turn his back to him again at step 5? If perp1 was still a threat, why did he re-approach perp1 at step 6, instead of taking cover at the back of the store?
What the victim did was not legally justified, IMHO.