indict vs let off

indict

verb
  • To make a formal accusation or indictment for a crime against (a party) by the findings of a jury, especially a grand jury. 

  • To accuse of wrongdoing; charge. 

let off

verb
  • To forgive and not punish. 

  • To cause to explode or come out; to release. 

How often have the words indict and let off occurred in a corpus of books? (source: Google Ngram Viewer )