My younger brother stole things from my parents house, its was small bits of money, tobacca pouch would disappeared and i had a game or 2 disappear out of my bedroom and he was never punished for it, he didnt have anything taken away or really made to own up to his actions and continiously lied about taking things and now hes a total waste of space, address it now and find out why he took it chances are he thought he could get away with it and you'd never fuiind out but in the case of my brother little things turned into bigger things and now he just sits in his room all day swearing at his xbox and not a thing is done about it because my parents cant talk about it rationally.
Good luck and hopefully hes got sense in him not to do it again.