Ohio Rev. Code Ann. § 2121.03

At the hearing the probate court shall hear such legally admissible evidence as is offered for the purpose of ascertaining whether the presumption of death is established. No person shall be disqualified to testify by reason of relationship as husband or wife to the presumed decedent, or by reason an interest in the presumed decedent's property, or because of a right or interest under the terms of a contract, beneficiary designation, trust, or otherwise, arising by reason of the death of the presumed decedent.