Child rapists and murderers tend not to fare well.
Raping a 1-month-old to death, particularly if it turns out to be your own child, will be considered a heinous crime by most inmates just as it is by the general public.
I heard of a guy who was in prison for raping (though not killing) his own teenaged daughter. He made the mistake of bragging about his crime to his new cell mate.
I was told that his body was unrecognizable when they finally pulled it out. (A relative of mine is a retired corrections officer in another state).
It turns out that the cell mate, who was in for a nonviolent crime, had a couple of teenaged daughters at home....
The NM prison system is one of the most violent around. My guess is he would be in some type of protected status.
I say a child rapist who gets massacred in jail finally got what he deserved.
What a sorry state of affairs when the best hope we have for justice are the sensibilities of his fellow inmates.