(1) If the department receives any information in accordance with section 7 regarding revenue leakage, or if information comes from any source, the department shall make necessary arrangements to secretly collect *evidence or prevent destruction of such information or information and immediately conduct a preliminary investigation.
(2) According to the preliminary investigation as per sub-section (1) or during the emergency investigation as per section 7, if it is found that someone has leaked the revenue or if there is reasonable grounds to suspect the leakage, an investigation officer shall be appointed as per section 10 for the investigation.
(3) The investigation officer designated as per sub-section (2) shall complete the work within six months from the date of commencement of the investigation and investigation.
(4) Notwithstanding anything written in sub-section (3), if the investigation and investigation work cannot be completed within the said period, the Director General may extend the deadline up to three months at one time or several times as required.