investigate vs scope out

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. 

scope out

verb
  • To examine; to scout; to investigate 

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