bloodhound vs police officer

bloodhound

noun
  • A detective or other person skilled at finding people or clues. 

  • A large scenthound famed for its ability to follow a scent many days old, over vast distances. This dog is often used as a police dog to track missing people, fleeing suspects, or escaped prisoners. 

police officer

noun
  • A peace officer who is a member of a police force. 

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