Very enlightening...
But the forensic evidence of the case wouldn't add up to him being convicted. He didn't know how to use a gun, he actually held it the wrong way and so he wouldn't be an obvious suspect.
They'd probably just check out the blowback of gunpowder, or fingerprints to see whether he did it. He wasn't wearing gloves so if his fingerprints weren't in the correct places on the gun that they needed to be to fire it then he couldn't have fired it. Also some gunpowder is blown backwards when a gun is fired, and some bounces of the target at that range, so they'd check his clothes for gunpowder (and blood if the blob people represented real people). Ballistic and finger print evidence could easily save him.
Also whoever reported the fight to the police could have said that one was Asian and the other black. There was virtually no case against him except that he was there, and he was holding (incorrectly) the murder weapon with a bemused expression (suggesting a very young age). I know you’re making a point about the cyclic nature of violence but I felt I had to point out these things. Otherwise excellent.