Nothing is really deleted from the internet. The police, however would not be able to do this without a legal court order. I doubt it was serious enough for the fbi to get involved with it(or the police), but they definitely would be able to track it.
Unless they did something incriminating, i'm sorry but law enforcement won't be able to work with you.
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.