DEATH PENALTY
WHEN LIFE GENERATES DEATH (LEGALLY)

IS IT EFFECTIVE AGAINST MURDERERS?

The argument most often used to support death penalty in former-Soviet republics is the necessity of having a particularly efficacious deterrent against murders and other common crimes. However, none of the many studies about the matter has been able to show that death penalty is more deterrent than other punishments.
It's completely wrong to think that most of those who commit serious crimes such as murders consider the consequences of their actions. Murders are often committed when the criminal is blinded with passion, when emotions prevail over reason. They are sometimes committed under the influence of drugs or alcohol, or in panic moments, when the culprit is discovered while he steals. Some murderers have very serious psychiatric problems or are mental patients. In none of these cases it's possible that the fear to be sentenced to death could act as an effective deterrent.
There is another heavy limit. One who plans a crime rationally can choose to go on, although he knows the risk he's running, thinking that he won't be discovered. Most of the criminologists assert that the best way to discourage murderers isn't increasing the severity of punishment, but increasing the possibility of discovering the crime and condemning the culprit.
Sometimes death penalty has opposite effects to the ones wanted. Those who know they risk to be sentenced to death can be encouraged to kill the witnesses of their crime or anyone who could be able to identify and incriminate them.
Finally, data about crime in abolitionist countries don't prove at all that the abolishment of death penalty has provoked its rise. In 1988 the UN Board for Crime Prevention conducted a study with existing data about the relation between death penalty and murder rate, concluding that:

The study couldn't offer scientific support to the thesis that capital punishment produces better results than life imprisonment and it's unlikely that evidence of it will be soon available. Even data, in fact, don't help thesis of deterrence.