examine vs investigate

examine

verb
  • to observe or inspect carefully or critically 

  • to interrogate 

  • to determine the aptitude, skills or qualifications of someone by subjecting them to an examination 

  • to check the health or condition of something or someone 

investigate

verb
  • To conduct an inquiry or examination. 

  • To inquire into or study in order to ascertain facts or information. 

  • To examine, look into, or scrutinize in order to discover something hidden or secret. 

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