(1) When any person subject to this Act has been absent from duty without due authority for a period of thirty days, a court of inquiry shall, as soon as practicable, be appointed by such authority and in such manner as may be prescribed; and such court shall, on oath or affirmation administered in the prescribed manner, inquire in respect of the absence of the person, and the deficiency, if any, in the property of the Government entrusted to his care, or in any arms, ammunition, equipment, instruments, clothing or accessories; and if satisfied of the fact of such absence without due authority or other sufficient cause, the court shall declare such absence and the period thereof and the said deficiency, if any, and the commanding officer of the unit to which the person belongs or is attached, shall make a record thereof in the prescribed manner.
     (2) If the person declared absent does not afterwards surrender or is not apprehended, he shall, for the purposes of this Act, be deemed to be a deserter.