blow the whistle vs tell the police about

blow the whistle

verb
  • To make a piercing sound which signals a referee's action or the end of a game. 

  • To disclose information to the public or to appropriate authorities concerning the illegal or socially harmful actions of a person or group, especially a corporation or government agency. 

tell the police about

How often have the words blow the whistle and tell the police about occurred in a corpus of books? (source: Google Ngram Viewer )