Stalin was poisoned

From Axis:

Stalin most likely has been poisoned by poison, sipped in a bottle of mineral water or smeared inside the glass used by the Soviet leader, the paper says. The chief of laboratory of poisons for secret murders, Grigory Mairanovsky, arrested right after Stalin’s death, in his letters to the KGB chief Beriya repented that substances prepared by him had appeared not so strong as he had advertised.

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