Well, one motivation for actually pulling the trigger on the first guy could be the handgun that was fired just seconds before by an armed protester. I don't see how self-defense wouldn't stick. Now, there are grounds for questioning an armed 17-year old running around, in what looks to be an active warzone, to say the least. But without that context, I don't see how you couldn't claim self-defense in both shooting incidents. He was firing towards armed men on both occasions, most likely fearing for his life, while actively trying to get away. To reiterate, the US is insane.