I read a book by G. M. Gilbert called "The Nuremberg Diaries". Gilbert was the prison psychiatrist before and during the trials.
He interviewed all the top prisoners, Goring, Hess, Ribbentrop, Rosenberg, Speer et al for, I guess, a couple of years.
Fascinating read in to the minds of the accused.
One thing that struck me was towards the end Gilbert was surprised most by the lack of remorse for what horrors they put people of all nations, soldiers and civilian, through and their total lack of empathy towards any of them.
He concluded: "Where there is no empathy, there you will find evil."