The Commissioner shall exercise general supervision over local investigators of fires and fire prevention inspectors. Whenever the Commissioner has reason to believe that the local inspectors are not doing their duty, he or his deputy shall make special trips of inspection and take proper steps to have all the provisions of the law relative to the investigation of fires and the prevention of fire waste enforced. (1905, c. 506, s. 6; Rev., s. 4690; C.S., s. 6270; 1925, c. 89; 1969, c. 1063, s. 2.)