The magistrate, before issuing the warrant, shall examine on oath the complainant and any witness the complainant may produce, and take their affidavits in writing, and cause them to be subscribed by the persons making the affidavits. The affidavits must set forth facts tending to establish the grounds of the application, or probable cause for believing the grounds exist.
Code 1932, § 11900; T.C.A. (orig. ed.), § 40-504.