culpable homicide vs murder one

culpable homicide

noun
  • Used other than figuratively or idiomatically: see culpable, homicide. 

  • Homicide which is culpable but does not rise to the level of murder; unlawful killing of a human being which does not constitute murder. 

murder one

noun
  • murder in the first degree. 

How often have the words culpable homicide and murder one occurred in a corpus of books? (source: Google Ngram Viewer )