ive read many times on here that christians dont have to follow the ten commandmetns or live by the laws and punishments as set by Moses. they apparently live by a 'spiritual law'.

so how does a christian deal with crime?

what would a christian do, for example, to a multiple murderer? do you forgive and let them go? do you put them in prison for the rest of their lives? or do you do what Moses said and kill them?