Section 46A. The director may upon his own initiative, in the case of any city, except Boston, or any town, and shall, when requested by the mayor or city council of any such city or the selectmen of any town, if conditions appear to the director to warrant it, investigate the accounts and financial transactions and affairs of such city or town, or of any department, board, commission or officer thereof. For the purpose of conducting such investigations, the director may employ such temporary investigators as may be necessary, who shall receive such compensation as the commissioner of revenue may fix and shall not be subject to chapter thirty-one. For the aforesaid purposes the director and his duly accredited investigators or agents shall have access to all necessary papers, vouchers, books and records. Upon the completion of such an investigation, a report thereon shall be made to the mayor and city council or to the selectmen, as the case may be, and a copy of the same shall be furnished to the attorney general, and to the city or town clerk who shall cause it or a summary of its essential features to be published at the expense of the city or town. A municipal officer or employee or a member of a municipal department, board or commission whose accounts or transactions are being investigated under this section shall afford to the director, his investigators and agents such assistance as they may require. Refusal or neglect by such an officer, employee or member to afford such assistance shall be punished by a fine of not more than five hundred dollars or by imprisonment for not more than one year, or both. The expenses incurred hereunder shall be paid primarily by the commonwealth; and the state treasurer shall issue a warrant requiring the assessors of the city or town concerned to assess a tax to the amount of said expenses, and such amounts shall be collected and paid to the state treasurer in the same manner and subject to the same penalties as state taxes. Any balance due shall be assessed in the succeeding years in the same manner as other state taxes.