Kids much younger than 13 know right from wrong, and are capable of understanding the harm they can cause. I don’t want to live in a society that thinks the problem here is “13” rather than “psychopath”.
Societal expectations for teens are far too low. We infantilize tweens and teens. We set our expectations so low that even when they outright murder someone, we blame everyone else.
If he’s murdering people at age 13, he learned how to be a scumbag criminal before he could talk.