Alma turns the people over the to the king. Why? He specifically says that it is to have them judged "according to their crimes." What crimes?
Mormon is never specific, and we have absolutely no specifics so that we might understand what their sins were. While they may have been sins of a religious nature, I suspect that the reason they are brought before the highest social judge of the land is because the nature of their sins is communal. They are disruptive to the fabric of society, and in that sense are deserving of judgment before the king.