It is unlawful for a sheriff or deputy sheriff to be concerned or interested, directly or indirectly, in the purchase of any property sold by him in his official capacity. If a sheriff or deputy sheriff has a concern or interest in the purchase at a sale made by him, he is guilty of a misdemeanor and, upon conviction, must be deprived of his office and fined in the discretion of the court or imprisoned not more than two years. A purchase made is null and void.