The only way of attempting to curtail these extreme acts of depravity are to fix the next generation.
Humans behaviour develops, according to experiences, influences, genetics & chance - while we can't make a perfect system, we do know enough on what can help.
Development of empathy is part of the key, it's a safeguard which prevents certain actions or makes them virtually impossible. We can attempt to reduce poverty (strong correlation with stress when struggling with bills/payment) - which you can't buy happiness, being poor can make some people unhappy/despondent & neglectful.
We can put in place social policies which catch these behaviour issues sooner (it's rare that a person has a great upbringing, never gets in any trouble, then starts murdering people - there are trends amongst killers & criminals which all relate back to early childhood).
Overall we need to ditch the traditional concepts of 'justice' & start to think about what actually works, look at the data - look at the evidence & make rational & sound choices off them. Looking globally we can already see that the depravity of 'human nature' differs vastly pending on location, this points all fingers towards environment & situation - two things we have the ability to mitigate against & control (to a varying degree).
Personally, I do see that kind of person as mentally ill. Nobody woke up one day with sound mind & decided to murder their own children then spend the rest of their life in prison. This is self-destructive behaviour which makes them completely unable to function in society (A definition which fits many other mental illnesses). The only thing is I'd prefer a new term to distinct between say autism & something learned externally.