Ohio Revised Code Title XXIX. Crimes Procedure § 2945.50

At any time after an issue of fact is joined upon an indictment, information, or an affidavit, the prosecution or the defendant may apply in writing to the court in which such indictment, information, or affidavit is pending for a commission to take the depositions of any witness. The court or a judge thereof may grant such commission and make an order stating in what manner and for what length of time notice shall be given to the prosecution or to the defendant, before such witness shall be examined.