When he gets sent to jail, make sure the other inmates know what he did. They will take care of him. That stuff does not go unpunished on the inside.
I’ll bet you are a meat eater and don’t mind eating many different animals that had to be slaughtered for your stomach.
You have undoubtedly killed mice or rats in your life. These are fellow mammals. Who made you God such that only your hand in killings was deemed “acceptable?”