This is book 4 of the "Clandestine Operations" series.

This note contains spoilers for the book.

Collaborating with his son, though to less harm to the series than usual.

Cronley is assigned to provide security to some of the judges and prosecutors at the Nuremberg trials, but also works on tracking down the missing Nazis running the Odessa Project. He does manage to catch them, but they escape between books (sorry, previews).

The horrors of the Holocaust are emphasized, and there's a major sub-plot about Himmler starting a new Nazi religion that nobody has heard of, yet has managed to infect half the German population (I never quite resolved that conflict). But it's vital that the criminals to be hanged be clearly established to be criminals rather than martyrs to the new religion.

And we have references without clarification to the Soviet security aparatus being Christian (a theme developed in more depth in the Argentine portions of these books). I'm not sure that means the same thing to his son that it does to me.