South Korean intelligence has questioned how North Korean leader Kim Jong-il died.
Citing US satellite photos, the National Intelligence Service says there was no sign that a special train, on which Mr Kim is reported to have been travelling when he died, had left Pyongyang.
State media announced on Sunday that Kim Jong-il, 69, died on Saturday of a heart attack.
NIS director Won Sei-Hoon said on Tuesday that the train was stationary at a Pyongyang station at the time of his death.
He said the train had not moved on Friday or Saturday.
According to media reports, legislators also asked about a rumour that Kim actually died at his residence on Friday night. Mr Won said he had heard the rumour but the NIS could not verify it.
