Well brother Islam demands death to the muslim who rejects Islam. I dont think that U need any reference for that. So naturally the girl who has turned murtad needs to be executed by her father, if she doesnt turn back to Islam and if her father is a true muslim. This is the Islamic position on this topic.
Now for being unjust who reject Islam, If U think that breaking their temples and idols, on which they have faith, is unjust than Islam demands that. Thats why pious muslims have broken so many temples and idols in the past. If U need any reference for this comment of mine than feel free to ask.
Peace.