Whenever in the opinion of the attorney general it shall appear that public interest requires an investigation, examination and/or audit of the books, records and accounts of any township or school district or any public officer thereof he may institute the same as provided herein. Such investigation, examination and/or audit shall not be ordered unless the same shall be requested in writing signed by at least 25 per cent of the registered electors of the township or school district setting forth specifically and in detail the reason therefor. Upon receipt of such request the attorney general may proceed and for that purpose may request the assistance of the auditor general or any of his clerks or assistants in the accounting division and may also call upon the prosecuting attorney of the county wherein such investigation, examination and/or audit is sought to be made for such help as he may deem necessary. It shall be the duty of the auditor general, his clerks or assistants and the prosecuting attorney to comply with such request. Fifty per centum of the expenses of the auditor general’s department with respect to such investigation, examination, and/or audit shall be a charge against the township or school district, and shall be paid from the general fund of the school district or the contingent fund of the township.