First, you alternated between nephew and nephews. You wouldn't want to separate these brothers. If I were you, I'd get a free (or very low cost) consult with a family lawyer.
This will be a long road, but it's not true that it's impossible. The problem is, you don't know your options. You also probably don't know what matters and what doesn't.
Any bruising, etc is visible proof. This is much more valuable in terms of evidence than "he said, she said". Courts can be reluctant to remove kids from bioparents (too much so), but obviously with their mom dead and their dad a jailbird, this is an unusual situation.
The other, lesser option is go down to the police station and ask to speak to someone about this. Sometimes the best way to get CPS involved is a police request. When you go down there, be very careful how you present information.
Focus on what you know for a fact, not things you've heard from the kids. Then, when you get a file started on this, and something happens, your call has a lot more cred than one coming out of the blue. Good luck with all this!
You can't. If you've called CPS and they've investigated with no result, then you cannot win custody. You would not be guaranteed custody anyway, even if the CPS report resulted in the childrens' removal.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.