G-d, too, remembers Holocaust: “Shall I leave their innocent blood unavenged? No, I will not.”
I will gather all nations and bring them down to the Valley of Jehoshaphat. There I will put them on trial for what they did to my inheritance, my people Israel, because they scattered my people among the nations and divided up my land…. Judah will be inhabited forever and Jerusalem through all generations. Shall I leave their innocent blood unavenged? No, I will not. The L-RD dwells in Zion! (Joel 3:2, 20-21)

Remains of Jewish victims executed by Nazis near the city of Zolochiv in Lviv province of western Ukraine (then USSR). German Nazi Einsatzkommandos (Mobile Nazi murder units) perpetrated mass shootings of Jewish civilians in Ukraine. The German photo above (taken by the Gestapo after the execution but before the grave was covered) was discovered by the Soviets at the former Gestapo headquarters after the liberation of the city in July 1944. From the documents of the Extraordinary Soviet Commission that was researching the Nazi crimes.