I don't consider myself a radical, rude or mean with my theory about these things, but here we go: Capital punishment works so very well based on modifying the concepts of Darwinism. If you murder other people, you get unselected. If you commit rape, you get unselected. If you kidnap and torture other people, you get unselected.
Killing your pregnant wife though? For that, I think the only fitting punishment is to have all of your fingers, toes, reproductive parts and kneecaps sawn off with a very very dull hacksaw, and then be left to bleed to death. Naw, that might be to nice, come to think of it. So my opinion? Him being put to death is inadequate. He deserves worse.