"Order and Annihilation" at the German Historical Museum also shows how for the most part, members of the police went unpunished after 1945, particularly in democratic West Germany. It helps to shatter a popular myth that until relatively recently was widespread, including among the country's modern force, that it was just the Gestapo secret police who got blood on their hands, organisers said.
They also played a decisive role in the persecution, rounding up and mass murder of Jews and and other "undesirables" both inside Germany and in Nazi-occupied Eastern Europe.
As harrowing photos and other exhibits show, police murder squads in the occupied territories would murder local civilians -- men, women and children -- including with special "gas trucks".
"Dear Hanna," one policeman wrote home from Ukraine. "We are in a little town. All the Jews are being killed. But don't think too much about it. It has to be done."
In the parts of the Soviet Union controlled by the Nazis alone, some 35 police units murdered more than a million people in 1941-2.
The exhibition, which runs to July 31, "follows directly on" from a successful recent one about Hitler that explored the personality cult of the Nazi dictator for the first time, museum head Hans Ottomeyer said.
After the war, very few police were brought to justice, with most able to continue in the force as the occupying powers sought to build a functioning state, although in communist East Germany this was much less the case.
The research that went into the exhibition, which includes some 500 exhibits, will also be used in police training.