Section 7(1)(b) in The Chennai Corporation (Superior) Service Pension Rules, 1970
(b)such departmental proceedings, if not instituted while the officer was in service, whether before his retirement or during his re-employment-(i)shall not be instituted save with the sanction of the Government;(ii)shall not be in respect of an event which took; place more than four years before such institution; and(iii)shall be conducted by such authority and in such place or places as the Government may direct and in accordance with the procedure applicable to the departmental proceedings in which an order of dismissal from service may be made in relation to the officer during his service; and