Some USA information on the deterrent value of capital punishment in the link below:

Quote from the article:
""One argument in support of capital punishment is that the threat of death deters murder more effectively than prison. However, research indicates that the death penalty is no more effective as a deterrent to murder than the punishment of life in jail. States with the death penalty on average do not have lower rates of homicide than states without the penalty.""

Comment:This statement assumes that "life in jail", means life in jail, not 25 years, nor 10 years before release in parole, as in some locals.


some USA material on deterrent value