OP, I'm staunchly against the death penalty and always have been, but when the details of what he'd done came out yesterday, even I wavered.
But no. We absolutely can't start killing those members of society we deem beyond the pale. It's not merely a matter of sometimes getting the verdict wrong. It's because it would be a massive moral shift for the country - there would be some people we deem less than human and therefore we can just dispose of them. It's an insidious attitude that I'm sure would creep into other areas of our society.
We have, unpalatable though it is, a duty of care to EVERYONE in our society. If someone has fallen this far, then we can't just blink him out because of what he's done. In this case, 'duty of care' looks like 'keep him away from everyone else, to stop him harming one more person' and completely curtailing his freedoms. He's very young and he's going to live out his entire life in prison, AND in a wheelchair with paralysis. That's going to be a hell of a lot more of a punishment than a quick death.
I'm not at all opposed to his rehabilitation, through prison-based therapies. Don't you think it would be a good thing, rather than a bad one, for a vicious and twisted man like him to realise what he's done, and the extent of his hatred for women, and start to address that? Doesn't mean I ever want him out of prison - I really hope he stays there.
I am so against the death penalty that I honestly don't think I could live in a country where it operates. I'd seriously consider leaving the UK, my home, if it was brought back here. It's a real line in the sand for me.