I was using a metaphorical "you", not you specifically.
You do not have to stoop to that level of force in order to deter a criminal.
And "not saving" anyone is Neutral, not Evil. Yes, caring more about your own skin than someone else's is not Evil.
You cannot know that Bob will become a repeat offender, and if you have the belief that he might do so, you would not release him in the first place.
It is not Evil by D&D's standards.