Sonny did. You don't murder someone for harassing your grown ass daughter. Alexis had already said she was going to go to a judge and even to his boss to complain that he was way overstepping and abusing his power. And then you have Anna, who witnessed the harassment when he was trying to throw Kristina in PCPD and she said she did not have the resources.
There were better ways to neutralize the man quickly without putting two bullets in him. He wasn't Peter. He wasn't Faison.
Sonny and John were not fighting over a gun. It wasn't self defense. He murdered an unarmed man.
