(6)The Commissioner shall keep in his custody the books of accounts, registers or documents seized under sub-section (3) for such period not later than the completion of all the proceedings under this Act in respect of years for which those books of accounts, registers or documents are relevant, as he considers necessary, and thereafter shall return the same to the dealer or any other person from whose custody or power they were seized:Provided that the Commissioner may, before returning such books of accounts or other documents as aforesaid, place or cause to be placed such marks of identification thereon as appear to him to be necessary:Provided further that the Commissioner may, before returning the books of accounts and other documents, require that the dealer or the person, as the case may be, shall give a written undertaking that the books of accounts and other documents shall be presented whenever required by any competent authority for any proceedings under this Act.
