My dear.. Your nephew does not show up to fires and he uses a vehicle that is supposed to remain at the fire station for things not related to the fire department. This is not a lie. It does not matter that Stacy gave him permission despite the grant used to purchase it. He knows right from wrong. He must know it is wrong to use the resources of this very small town and thus the money of the people here for his own gain. He has the opportunity to disprove the claims against him. Show the mileage and gas logs for the fire department vehicle.
As a side note it is lovely that you are defending your nephew when your own son has been harmed by this situation and yet you say not one word about him or in defense of his choices.