Okla. Stat. tit. 22, § 22-711: Service of subpoena by whom - Return

A peace officer must serve in his county, city, town or village,

as the case may be, any subpoena delivered to him for service,

either on the part of the state or of the defendant, and must make a

written return of the service, subscribed by him, stating the time

and place of service without delay. A subpoena may, however, be

served by any other person.