I have a highly industrialized country that is rapidly economically growing, all the while expanding its territory (think along the lines of the USA's territorial expansion between 1820 - 1840.) There are a significant number of new settlements that are appearing, often the size of towns or small cities, with few people venturing out of these settlements due to the harsh conditions outside.
Crime is evident everywhere within these settlements, and as a result the central government authorizes civil servants in these new settlements to appoint watchmen to carry out law enforcement in these communities - but there is still the large issue of corruption, as most watchmen endure poor work conditions and large criminal syndicates are rife.
I want to create a new law enforcement organization (LEO) within this world that will act as a general law enforcement agency for combating crime throughout these new territories, as well as rooting out corrupt watchmen. How would this new organization function? Are there any existing examples of LEOs as I have described?
Please note that this new LEO to not be slightly related to the watchmen, I want watchmen to see this new agency as the police that enforce law within the regular police. I drew some inspiration for this world from the American Wild West.