This is even older picture of my Grand Grandfather, who was high level officer of Yi Dynasty. 

He was an Am-Haeng-Eu-Sa, Secret Agent of King, for many years who confidentially observe the local governors in the street talking with citizens pretending he is a regular citizen or even a beggar, find any bad governors, shows up suddenly in the office of governor, if he is found to be corrupted, and make the correction at the spot with absolute power of firing him and/or putting him into jail. It was the most scary and powerful officer for all country governors in Yi Dynasty.