case officer vs ganger

case officer

noun
  • A person assigned to manage a client's affairs. 

  • In intelligence organisations, a person who manages a network of agents. 

ganger

noun
  • One who oversees a gang of workmen. 

  • One who is employed in conveying the coal through the gangways. 

  • One who or that which walks or goes; a goer; a walker. 

  • A horse that goes quickly. 

  • A length of chain, one end of which is fastened to an anchor when let go, when the other end is fastened to a hawser. 

How often have the words case officer and ganger occurred in a corpus of books? (source: Google Ngram Viewer )