Agree.
I live in the US, where some states impose the death penalty. I disagree with it because it manifestly doesn't serve as a deterrent, miscarriages of justice are too frequent, and because it cheapens life and encourages brutality of attitudes.
I read somewhere in relation to the murder of Huntley that he had worn a Man Utd jersey in the runup to the attack, and that this had been seen as a provocation.
I think the news of the murder and the knowledge of previous attacks really underline the very obvious fact that prisons are peopled by individuals who do not abide by the laws other people do. I don't say this to be flippant - what I mean is that inmates have their own codes and enforce their own rules, and there is a hierarchy among them just as there is on the outside.
Just as on the outside many prisoners found ways to get away with crimes, they do so within prisons. We do not know how many attacks are foiled annually by prison staff, so I don't think it's appropriate to write off the system on the basis of one or two highly publicised attacks every year.
Ironically, the efforts to create humane environments in prisons often result in prisoners gaining access to materials that can be turned into murder weapons, and the provision of opportunities to work and socialise provide the close physical proximity necessary.