Soviet Historiography and the Holocaust
Soviet use of the Holocaust as a propaganda tool, first against Germany, then against the nations the USSR occupied after WWII, commenced with Germany's invasion. Nor were the Soviets above blaming the Nazis for their own atrocities as at Katyn, not officially acknowledged until 1989.
That use peaked in the 1970's as the KGB provided U.S. and Canadian authorities with evidence implicating Baltic and Ukrainian individuals in Nazi atrocities. This evidence—provided with no expectation or demand for quid pro quo—was not always reliable: accusing those who were children at the time, deposing the deceased, and referencing trial "transcripts" published prior to trial. Soviet propagandists produced Daugavas Vanagi, Who Are They? (1963) and the lesser known There Shall be Retribution: Nazi War Criminals and Their Protectors (1984) aimed at discrediting the leadership of the Latvian émigré communitiy in the U.S., and The SS Werewolves (1982), similarly directed against the Ukrainian community in Canada.
Still, as with Nazi archives, judicious study of Soviet-era archival resources offers the possibility of separating facts from fabrications of history.