Ohio Revised Code Title XXIX. Crimes Procedure § 2945.59

In any criminal case in which the defendant's motive or intent, the absence of mistake or accident on his part, or the defendant's scheme, plan, or system in doing an act is material, any acts of the defendant which tend to show his motive or intent, the absence of mistake or accident on his part, or the defendant's scheme, plan, or system in doing the act in question may be proved, whether they are contemporaneous with or prior or subsequent thereto, notwithstanding that such proof may show or tend to show the commission of another crime by the defendant.