Let's hypothesise then.
One of your relatives, who you had gone to see that day, was found dead sometime later. You were the last person seen leaving the building. You are (wrongly as it happens) the main suspect. You are wrongly convicted. You receive the death sentence.
Do you still favour the death penalty? (a simple yes or no).
Wrongful conviction is a different issue, I wouldn't favour the death penalty in all cases,but some murderers are so evil they don't deserve to live, where there is an element of doubt as in the barry george case i wouldn't favour the death penalty, but if you take the case of ian huntley then yes i would favour it.
The object of capital punishment was to deter and punish, if it is proven that capital punishment reduces the murder rate then why not have it, hundreds of lives could be saved every year.
As for wrongful convictions, what is needed is an honest debate on this issue, the truth is no system is foolproof yes there are going to be wrongful convictions to-day and in the future, if you go into hospital there is a chance a mistake could be made during an operation and you could lose your life but we don't close down hospitals because we know that sooner or later mistakes will happen, likewise with driving we don't ban cars because mistakes are made and people crash. The object of capital punishment should be to reduce the number of homicides it isn't about being cruel, the risk of wrongful conviction should be balanced against the number of lives saved by the deterrant effect of capital punishment.