Many contend that the use of capital punishment as a form of deterrence does not work, as there are no fewer murders on a per-capita basis in countries or states that do have it, then those that do not. In order for capital punishment to work as a deterrence, certain events must be present in the criminal's mind prior to committing the offence. The criminal must be aware that others have been punished in the past for the offence that he or she is planning, and that what happened to another individual who committed this offence, can also happen to me. But individuals who commit any types of crime ranging from auto theft to 1st-Degree Murder, never take into account the consequences of their actions. Deterrence to crime, is rooted in the individuals themselves.
Every human has a personal set of conduct.
How much they will and will not tolerate. How far they will and will not go. This personal set of conduct can be made or be broken by friends, influences, family, home, life, etc. An individual who is never taught some sort of restraint as a child, will probably never understand any limit as to what they can do, until they have learned it themselves. Therefore, capital punishment will never truly work as a deterrent, because of human nature to ignore practised advice and to self learn.