A person appearing before either house, or both, or a legislative committee in response to a subpoena is entitled to $20 for each day's attendance, and for the time necessary in coming and returning to the person's place of residence and mileage at the rate of 15 cents a mile for the distance traveled in going to and returning from the place of attendance. The witness fee and mileage fee shall be paid out of the state treasury upon presentation of a certificate of attendance and mileage due, signed by the presiding officer of the house that authorized issuance of subpoena.