After the end of World War II, as a result of the Potsdam Conference, Königsberg found itself within the borders of the Soviet Union.

An excerpt from the article 24 facts about Kaliningrad

In 1946, the city's name was changed to Kaliningrad, in honor of the late Mikhail Kalinin, a Bolshevik responsible for many mass communist crimes.

Kalinin's signature (among others) appears on the decision to murder Polish officers in Katyn in 1940.