Very simple really, serial killers, serial sex offenders, child molesters should either be hung, eletric chair or leathal injection (or possibly all 3). That's all there is to it, if they are repeat offenders then they're not going to change there ways, they're wasting our taxes and they're filling up the jails. No maybe they could be usful, why not have them used for medical experiments, save using animals right? That way ok they die, but their last act will be one the benifits the community (for a change!).