If this really happened, then I wonder if she was drugged. I'm reminded of the book-turned-film "The Serpent and the Rainbow". It delt with Haitian voodoo and a white powder/dust that, when blown at one's face, would render the person dead, but not dead. The heart stops and all motor functions are temporarily paralyzed, unable to move so much as an eye. The person was assumed dead and so they would be buried alive - only to 'awaken', regaining function, but too late.
However, I wonder something else - Do they not use embalming fluid in Russia? If so, then she would've been dead already.