Why does yu tsun kill dr. albert at the end of borges’s “the garden of forking paths”?

Which excerpt from the war of the worldseffectively reveals how the author relates the climax of the narrative through the narrator's thoughts? the war of the worldsall this had happened with such swiftness that i had stood motionless, dumbfounded and dazzled by the flashes of light. had that death swept through a full circle, it must inevitably have slain me in my surprise. but it passed and spared me, and left the night about me suddenly dark and unfamiliar.and then, with a renewed horror, i saw a round, black object bobbing up and down on the edge of the pit. it was the head of the shopman who had fallen in, but showing as a little black object against the hot western sun.at that time it was quite clear in my own mind that the thing had come from the planet mars, but i judged it improbable that it contained any living creature. i thought the unscrewing might be automatic.my mind ran fancifully on the possibilities of its containing manuscript, on the difficulties in translation that might arise, whether we should find coins and models in it, and so forth. yet it was a little too large for assurance on this idea. i felt an impatience to see it opened.