What should I do if my child has stolen some candy from a convenience store? How does one approach this situation?

You should probable develop a bit of hesitation in your child nature while he does that hence forth. Like Imagine a condition : A child knows he should finish his homework else teacher will scold him so he hesitates to anything else before completing his homework.. So you should be framed more as a teacher in those condition. And to achieve this explain twice but if he continuous you should scold NOT SAY but ONLY ONCE effective enough that he remembers. Probably scolding from dad will be more effective. Remember only once.