See ... that is the truly GREAT thing about a Republic ... when an office is vacant you can just step in and fill it. This goes for any office ... including that of president. When Bush vacated the office of president 'Bama happened to be wandering by and volunteered to fill it.
This is called the De Facto principle.
As far as the office of sheriff being replaced with a State Marshal .... what an administrative subdivision of the United States does actually has very little to do with the workings of one of the de jure several States of the union. Not that they don't try to convince you that they have the power to change things ... but they don't.