A year after the death of Kim Jong Il, little information has emerged about the circumstances of his reported heart attack other than the official narrative that he died from overwork at 8:30am on Dec. 17 aboard his personal train while heading out on another "field guidance" trip.

Doubts about parts of that account have been raised, including skepticism about whether Mr. Kim was actually on the train given his apparent habit of sleeping in late, and satellite images showing the train still in Pyongyang.

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