Kid keeps talking about killing people, cleaning the mess and hiding the body.

Kid keeps talking about killing people, cleaning the mess and hiding the body. He's 6 years old and doesn't have a violent past. His mom spoils him and he's never been in a foster home. So I'm not understanding this. I've never had a kids, that I watch, that's like this. When he leaves someplace, gets time out or even when someone tells him not to do something, he says he hate that person , he wishes you were dead or that he wishes he could kill you. He's very smart and sneaky. I worried he's a psychopath or sociopath or maybe he's just young.