I do know exactly what you mean. It's hard to imagine how someone as dysfunctional as that man clearly is - not just that he has brutally murdered his own baby but that it seems to have been done in a premeditated, psychopathic way out of a pathological desire to maintain control over the baby's mother -can ever not be a risk and a burden to everyone around him. Violent, controlling men are like rabid dogs really and there's quite a lot of evidence out there that they aren't really reformable.
Still, I think the death penalty, where it is avoidable, as it is in our society, probably brings more problems than it solves. Let's forget the obvious (and in this case not especially applicable) problem of false conviction... What does it do to society to sanction murder, however "deserved" some may feel it to be? Who carries out the sentence and what does it do to those involved? What are the potentially unforseen pragmatic impacts (eg juries less willing to convict, vast legal expense of death row appeals etc)?
I do think being a violent controlling man should come with some kind of label (similar or equivalent to a psychiatric diagnosis) which enables the state to incarcerate / parole indefinitely and in total separation to women and children. Maybe he could be capable of forming positive relationships with other toxic men and they could achieve something useful with their lives in a work programme or something. Personally I'm not about revenge. I have some pity for people who are basically the human equivalent of a feral animal, and I think it's better to try to make some use of their lives instead of kill them. Killing is a sick thing to do and I think the death penalty makes society sick.