Point of order. I'm pretty sure that Ian Huntley is still in a mainstream prison and has never spent time in a psychiatric institution. Also, don't forget that Ian Brady was fit to plea at his trial and didn't enter psychiatric care until he'd been behind bars for nearly twenty years.
I don't believe in the biblical eye for an eye but the question I was raising is whether the death penalty is right for someone who is "not all there". But a kind of reverse Catch 22 argument is that you have to be wrong in the head to murder someone. There are also degrees of bonkersness in the judicial system. One does not need to be totally off one's rocker to pursue a claim for diminished responsibility.
Another argument against the death penalty is the question of whether it is good for society as a whole. Evidence has been presented in the past recording rises in violent crime around the time of executions.
It also seems pretty clear that many murderers are products of deprived or violent families and sometimes the origins of this violence were what we might call "state sponsored". Mira Hindley's father was an ex-para in the Second World War when his propensity for violence against the enemy would have been regarded as commendable. But when he applied this violence to the upbringing of his daughter it created a woman not only anaesthetised to suffering but probably also taking pleasure from exercising power and seeing others suffer.
Meeting brutality with brutality is not the way to create a civilised society.
One can only imagine how the boy must have suffered before he died. Whether it was madness, despair, or any combination of both on the mother's part, I have to admit that this is where the eye-for-an eye stuff starts sounding good to me. However I am opposed to the death penalty for all of the reasons Godot and the others mentioned and also because her death would not bring the child back.
It was fundamentally wrong for this woman to play god with her child's life, and in my opinion it would be just as wrong for the state to take this same responsibility regarding the mother's life upon itself, for whatever reason.