Ohio Rev. Code § 5301.12: Purchaser at tax sale.

When real estate is sold at tax sale, and the purchaser has received a deed therefor, and it has been placed upon the tax duplicate in his name, or those claiming under him, who openly and notoriously claim the title and ownership to such property, and pay the taxes thereon, as against any title acquired by deed executed after such tax sale, such facts are prima-facie evidence of the possession of such real estate by such purchaser, or those holding under him, from the date of such sale until it is set aside or redeemed. The knowledge, by a person acquiring title by deed executed after such tax sale, of the payment of taxes, and the claim of title and ownership shall, as to him, be conclusive proof of possession.