Kim Jong-un's sister Yo-jong has not been seen in public for seven months despite having apparently been given a plum job in the Workers Party's propaganda department.
The question of her whereabouts has come into fresh focus with the assassination of Kim's half-brother Jong-nam in Malaysia on Monday amid fears of a bloody cleanup in his immediate family.
Kim Jong-un has executed his uncle Jang Song-taek and shunted his other uncle Kim Pyong-il from his perennial post as ambassador to Poland to the Czech Republic to weaken his position.
Kim Yo-jong's last public appearance was when the official Rodong Sinmun daily carried a photo of her holding up her ID card at a session of the rubberstamp Supreme People's Assembly on June 29 last year.
But she is thought to be on good terms with her brother and run his personal security. When she was elected to the Workers Party's central committee last year, many observers speculated that she would soon be elected to the politburo.
In October, the National Intelligence Service here attributed her disappearance to pregnancy or illness.
Since an unprecedented admission of "shortcomings" in his New Year's address, Kim Jong-un has waged a brutal cleanup campaign, including firing the minister of state security and executing other senior officials.
Kim Pyong-il could be a primary target if Kim Jong-un decides to get rid himself of all other relatives who pose a potential threat.
He was born to Kim Il-sung's second wife Kim Song-ae but lost out in a power struggle with his half-brother Kim Jong-il and was sent off into padded exile in 1979.
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