Ohio Rev. Code Ann. § 2945.45

In all criminal cases, the clerk of the court of common pleas, upon a praecipe being filed, shall issue writs of subpoena for the witnesses names therein, directed to the sheriff of such county, or the county where such witnesses reside or are found, which shall be served and returned as in other cases. Such sheriff, by writing indorsed on the writs, may depute a disinterested person to serve and return them. The person so deputed to serve such subpoenas shall make a return of the service made, and make oath thereto before a person competent to administer oaths, which shall be indorsed on the writ. The return may be forwarded through the post office, or otherwise.