It appears to be the case that people commit crimes out of passion, compulsion, or planning with reference to some desired good. Crimes of passion cannot be deterred since one doesn’t think carefully (or at all) when one commits a crime of passion. A man isn’t going to think about his life in relation to the death penalty when he comes home, finds his wife with another man, and murders him in a rage. Crimes that flow from compulsion—whether internal in the form of some mental illness or external in the form of physical force, blackmail, etc.—will also be unaffected by deterrence strategies. And if a man is seriously planning a murder then presumably he doesn’t think he will get caught…otherwise why would he plan in the first place?