my nigga thats not how law works. Even if he was satan himself the law wouldn't just shrug it off because he was bad. 3 men, one of them armed, killed an armed man where they could have restrained him. Thats how law sees it.
I'm guessing the author is going for a more realistic narrative here where MC can fuck up and they're not invulnerable. It also adds more satisfaction and anticipation for when the revenge happens.