Where any document—

(i) is produced or furnished by any person or has been seized from the custody or control of any person, in either case, under this Act or under any other law, or

(ii) has been received from any place outside India (duly authenticated by such authority or person and in such manner as may be prescribed by the Central Government) in the course of investigation of any offence under this Act alleged to have been committed by a person,

(a) presume, unless the contrary is proved, that the signature and every other part of such document which purports to be in the handwriting of any particular person or which the court may reasonably assume to have been signed by, or to be in the handwriting of, any particular person, is in that person's handwriting; and in the case of a document executed or attested, that it was executed or attested by the person by whom it purports to have been so executed or attested;

(b) admit the document in evidence, notwithstanding that it is not duly stamped, if such document is otherwise admissible in evidence;

(c) in a case falling under clause (i), also presume, unless the contrary is proved, the truth of the contents of such document.