BERLIN — For all the efforts Germany has made in coming to terms with its Nazi past, the fate of one of the prime architects of the Holocaust has long eluded the authorities and historians.

Heinrich Müller — the chief of Hitler’s dreaded Gestapo, or secret police — was one of the most senior Nazis to escape capture or certified death at the end of World War II. Holocaust historians say that Western investigators, at the very least, looked for him intensively for years after 1945, and there were reports placing him everywhere from Czechoslovakia to the Soviet Union or even Brazil.

Now, the question of Müller’s fate has taken a disturbing twist, as Prof. Johannes Tuchel, head of an association that watches over memorials to German resistance fighters, claims to have uncovered a document indicating that he was killed, probably on May 1, 1945, hastily buried in a provisional grave near the Nazi Air Force ministry, and later reburied in a mass grave in the Jewish cemetery in Mitte, in the heart of Berlin.

While the claim is not definitive — lacking, for instance, any forensic verification — it was credible enough to stir a mixture of sorrow, outrage and shock in this city where so much blood and treasure have been spent, and beyond.