After a felony has been committed, and before any arrest has been made, the prosecuting attorney of the county, or any judge or magistrate, may cause subpoenas to issue, returnable before any court or magistrate, for any person to give information concerning such felony. The subpoenas shall require the witness to appear forthwith. Before such witness is required to give any information, he must be informed of the purpose of the inquiry, and that he is required to tell the truth concerning the same. He shall then be sworn and be examined under oath by the prosecuting attorney, or the court or magistrate, subject to the constitutional rights of the witness. Such examination shall be taken in writing in any form, and shall be filed with the court or magistrate taking the testimony. Witness fees shall be paid to such persons as in other cases.