Depends on what, if anything, he is charged with, but he needs a lawyer ASAP, and should not make any statements to anybody concerning this matter, especially not to anyone "investigating" this matter, until he has talked to an attorney. It is possible that he could face felony charges and prison time.
It's hard to say right now if there is only an investigation. We don't know at this point what he may end up getting charged with. Once charges are brought, you should hire an attorney immediately.