António de Oliveira Salazar interest in chess was a clear 0 (zero), Josef Stalin interest in chess was like what? In his last games Alekhine draw with people as notable as Perez, Frias and Lupi. Stalin was so worried...
The Soviets coveted the championship title for its propaganda value, and the Chekists in the government had a score to settle with the "traitor." The immediate post-war political situation in Soviet-occupied Europe was tense, especially Germany, Austria, Czechoslovakia, and the Balkans. Intrigue was everywhere
Koltanowski personally told me that he killed himself. Alekhine just wasn't important enough to murder.
I believe he told you that, but how would Koltanowski know? He was on chess tour in Central America when the Nazis invaded Belgium, and avoided the Holocaust. We can place him in NYC in 1944, where he met his future wife. If he still had surviving contacts in Europe in 1946, his knowledge of Alekhine's death was hearsay.