I support the death penalty in cases where it's 100% certain they're guilty. Why fuck around spending money on looking after them for the rest of their lives when there are more important things to spend money on?
tbh I think the best thing would be to test things on them.
People are always moaning about how we have to test things on animals. Well solve two problems at once - plenty of human guinea pigs to use, while saving the innocent monkeys and rats. It'd give more accurate results as well - we're more genetically similar to Ian Huntley or Ted Bundy than to a rat (unfortunately)