Just depends on how cutthroat the world is ig as well as if there skill users who can detect lies. Also just killing her wouldn't solve everything since it might need even more death (her parents for one) to cover it up which would lead to even more trouble versus just giving them some cash as...
The MC could break most bones on their body just enough to not be fatal, tear their teeth from the gums, force feed them bugs and garbage, stop them from breathing for a minute or two etc. in terms of direct physical abuse. He could also just tweak their body a little bit to cause them constant...