Killing a person as a punisment for a crime, is called capital punishment. It has been performed since the dawn of men, and is still performed in several places around the world. It is most common in dictatorships, but it is also performed in places wich are usually considered more or less liberal, such as the USA. Each year, 250 people are added to the so-called death row and 35 executed in the united states of freedom. Death row is what they call the row of people who have been sentenced to death, and are waiting for their own execution. People often have to wait several years in the death row. The average time from one is sentenced to the actual execution is 8 years. Convicts usually appeal several times, wich is a time-consuming prosess.
There are different oppinions on capital punishment. Basically, you can either be pro or con. The people settling for pro thinks death is a suitable punishment for serious crimes such as murder. After all, if a person has killed once, he can easily kill again. A reasonable alternative is locking the convict up for the rest of his natural life. Another argument pro capital punishment, however, concerns the economical aspects. If you are to lock a person up for several decades, it would take a serious amount of money. Killing the convict saves the government a lot of money.
On the other side, you can never be certain you have sentenced the right person, and people can actually change with time. Some people committs murder without actually intending to do just that. And anyways, putting the murderer to death cannot bring the victim back to life.
After all, capital punishment seems a good solution to the most serious crimes, but it depends entirely on the situation. If a person murders in self-defence, a death sentence does not seem like a fair solution. If a person plans a murder and then goes through with his plan, however, death would be a suitable punishment.