aggravating circumstance vs heat of passion

aggravating circumstance

noun
  • A factor that increases the culpability or deleterious consequences of a wrongful act. 

heat of passion

noun
  • An outburst of anger that leads one to commit a criminal act, and is itself influenced by preceding events that might cause a reasonable person to lose self control. 

How often have the words aggravating circumstance and heat of passion occurred in a corpus of books? (source: Google Ngram Viewer )