cast about vs investigate

cast about

verb
  • To try to find; look around; search. 

  • To plan; plot; contrive. 

investigate

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

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

  • To conduct an inquiry or examination. 

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