Firstly, no matter how many criminals we may kill or have killed, it never brought any victims back or even prevented any new victims being created. Thus I cannot agree the position that Capital Punishment brings about any re-valuation of human life. (the side that supports capital punishment may argue that abolishing it results in the devaluation of respect for human life)
Also, those who tend to argue against Capital Punishment worry less about state sanctioned killing or more likely state sanctioned revenge than the worry that an innocent may be wrongly killed as has happened before. One innocent killed by the state is worse than 100 proven murderers being killed in my opinion and I believe in the opinion of those groups that oppose the death penalty.
Personally, I would agree death sentence for paedophiles only as it seems these are the only people who cannot be changed of their condition - I was in favour of chemical castration but now I read it doesn't always work. I'd rather see as Tashah states proper life sentences for convicted killers and without the little luxuries many prisoners take for granted now.
If a society chooses to have death sentences then I would want that society to make 100% sure the perpetrator is 100% guilty of the crime.