- The Treasurer of Puerto Rico, or his duly authorized agents,

are hereby invested with authority to conduct such investigations as they shall deem necessary for the purpose of determining the truth of any fact or state_ ment given to obtain the property tax exemption granted by law; provided however, that upon the refusal of any tax payer to permit the inspection of any premises or bond or aging warehouse, or upon its refusal to permit the inspection of its books or records, the Treasurer may deny the petition for exemption or cancel the same if already granted.