Wis. Stat. § 63.20
Any person who is served with a subpoena to appear and testify or to produce books and papers, issued by the board of city service commissioners in the course of any investigation conducted under ss. 63.18 to 63.53, and who refuses or neglects to appear and testify or to produce books and papers relevant to the investigation, as commanded in the subpoena, shall be guilty of a misdemeanor, and shall on conviction be punished by a fine or imprisonment or both, as provided under ss. 63.18 to 63.53. The fees of witnesses for attendance and travel shall be the same as the fees of witnesses before the circuit courts of this state, and shall be paid from the appropriation for the expenses of the board. Any circuit court of this state or any judge thereof, upon application of the board, may compel the attendance of witnesses, the production of books and papers and giving of testimony before the board by attachment for contempt or otherwise, in the same manner as the production of evidence may be compelled before the court. Every person, who takes an oath or makes affirmation before a commissioner in the course of the investigation, and swears or affirms willfully, corruptly and falsely, shall be guilty of perjury, and upon conviction shall be punished accordingly.
Wis. Stat. § 63.20