The supervising department, in aid of the investigation of any institution under its control, may summon and compel the attendance of witnesses and examine the same under oath, which any member thereof shall have the power to administer. The supervising department shall have access to all books, accounts, papers, and property material to such investigation and may order the production of any other books or papers material thereto. Witnesses other than those in the employ of the state are entitled to the same fees as are allowed in civil cases in the district court. The claim that any testimony or evidence sought to be elicited or produced on such examination may tend to incriminate the person giving or producing it, or expose that person to public ignominy, does not excuse that person from testifying or producing evidence, documentary or otherwise, but no person may be prosecuted or subjected to any penalty or forfeiture for and on account of any matter or thing concerning which the person may testify or produce such evidence. The witness is not exempt from prosecution and punishment for perjury committed in so testifying.