The things he had controversial views about were not something I, for one, would associate with lefty politics - LGBT rights, abortion and the like from his strong Catholic Faith and so, to be fair, things he was committed to. And things I would have strongly disagree with him on.
On the other...
Without googling anything, I can think of at least two cases where people were wrongly hanged - Timothy Evans, and the case of Craig and Bentley.
And there have been a number of cases since the death penalty was taken out where people have wrongly been convicted of murder - the Birmingham six...
I would be a political opponent of his, but he was a decent, kind and principled man. Awful that this happens when going about normal constituency business.
And I don’t think capital punishment would make any difference whatsoever.