M.R.
I would suggest that you call the school guidence counselor and tell her what is going on with your family right now. The counselor may be able to help you find resources so that there is alway food for your son, that is part of what they do. He will be distracted if he is hungry and worred about the whole situation, and he is probably worried about you too.
If he had anything to do with the laptop being stolen, then he also brought it back, which means he knows right from wrong and felt badly. If he did not have anything to do with it, and you trust him and he says he just found it, then stand up for him and defend him to the principal, and if they have any other evidence that it was your son, listen respectfully. Just use your best judgement.
What ever happens, make the contact with people who can make sure that your son always has breakfast, lunch and dinner. They are there to help you!
M.