Also we only have the sound of the dude screaming as evidence that he died. Regan could have made that noise easy enough, if, for instance, she didn't *want* to kill the tech for whatever reason. (Squeamish. Wants a pet. Bored. Her hands are sore from being tied up and she wants someone to open doors and carry stuff for her.) I think it would 100% fit that family if she lied to daddy and had her own stuff going on.