SEOUL, South Korea — Researchers scrutinizing North Korea’s official images and lists of mourners paying respects to Kim Jong-il have noticed two conspicuous absences: the elder brothers of Kim Jong-un, the appointed heir.

They have also been buzzing about the appearance of Kim Ok, one of Kim Jong-il’s closest aides, who has served as the North’s de facto first lady since Kim Jong-un’s mother died in 2004. She showed up on Wednesday in the North’s press coverage of mourners at the Kumsusan mausoleum in Pyongyang, the capital, where Kim Jong-il’s body has been on display in a glass coffin since the official announcement of his death on Monday.

Identifying the mourners and absentees in the world’s most closed society is one of the few ways available to outsiders trying to solve the mystery of the unfolding succession in Pyongyang. They are looking for any clues about whether Kim Jong-un, the second son of Kim Jong-il’s third wife, will be able to assert control over the monolithic dictatorship established by his father and grandfather.

Similar questions hung over Kim Jong-il when he was anointed North Korea’s leader in 1994. But the intrigue is much deeper this time because of Kim Jong-un’s youth and inexperience and the convoluted relations in the extended Kim family.