The receiver within twenty days after his appointment, and the assignees within twenty days after the meeting of the creditors, shall file a sworn inventory of the estate, with its then present value. For the purpose of enabling them to do so or to file any supplementary inventory, they are hereby empowered to examine the insolvent, under oath, as to any matter appertaining to such assets, and by leave of the court to call before them, by subpœna, with or without his books and papers, or the books and papers of any firm, limited partnership, joint-stock company, or corporation with which he is connected; and examine also, under oath, on the same subject, any person who they have reason to believe has knowledge of other or further assets of the insolvent's estate, or can give them information touching the same. No objection to such examination shall be made on the ground that a disclosure would tend to bring the witness into contempt, or disgrace or convict him of crime; but the information thus obtained shall not be used against him in any other proceeding. Any witness may decline to answer any question, or produce any books and papers, which, aside from the foregoing, he would not be required to answer or to produce in court upon a trial involving the same questions. Every witness, including the insolvent, shall be entitled to receive, out of the insolvent's estate, the usual witness fee and mileage for his attendance for this purpose.