She was first identified as Kim Jong-un’s old flame 13 months ago, in July 2012. The poised, coiffed and elegantly dressed companion of the North Korean dictator of Kim Jong-un was filmed sitting next to him at a concert in Pyongyang, then ascending the stage with him to applaud the performers. One month later, however, she vanished from the scene as abruptly as she had arrived. And today came the shocking news that Hyon Song-wol, one of the reclusive state’s most popular singers, had been executed by machine gun.

Eleven other members of her pop group were reportedly executed with her earlier this month, accused of filming themselves having sex with each other then selling the videos.

Other musicians linked to the 12 who allegedly died were forced to watch the grisly killings, then sent to labour camps, victims of the reclusive regime’s policy of collective punishment. South Korean Pyongyang watchers had named Ms Hyon as Kim’s girlfriend when he was a teenager. His father, Kim Jong-il, was said to have disapproved of the relationship and forced his son to break it off. The fresh encounter with his sweetheart was interpreted as evidence that the youngest Kim was shaking off his father’s influence and taking his own decisions.

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Whether the woman photographed with the young leader really was the singing star has never been clarified. A fortnight later, when Kim was photographed with another young woman on his arm at the opening of a Pyongyang amusement park, North Korea’s official media pointedly identified her as “his wife, Comrade Ri Sol-ju” – a woman who had performed with the same group as Hyon Song-wol.

This terse announcement was a revolution in North Korean terms, where until now the private lives of the rulers had been kept strictly secret.

Hyon Song-wol’s patriotic hits included “Footsteps of Soldiers”, “I Love Pyongyang”, “She is a Discharged Soldier”, “We Are Troops of the Party”, and “Excellent Horse-like Lady”.

Why she and her fellow musicians should have been reduced to selling videos of themselves having sex, and why this severely proscribed activity should have been punished in such a cruel and public fashion, remains a mystery.

Chosun Ilbo, the respected South Korean daily with sales of over two million, reported that Hyon Song-wol and her colleagues had been arrested on 17 August for breaking pornography laws. Their public execution took place three days later, with other members of North Korea’s most famous pop groups force to watch before being dispatched to prison camps, from which few prisoners return.

The severity of the punishment indicated that there was a political dimension to the case, according to one Japanese authority on North Korean affairs. Professor Toshimitsu Shigemura of Waseda University in Tokyo told The Daily Telegraph, “If these people had only made pornographic videos, then it is simply not believable that their punishment was execution. They could have been made to disappear into the prison system instead.”

Such a hideous fate could only be explained if the singer and her comrades had been identified with a rival power faction in Pyongyang, the professor went on. An alternative explanation was that the elegant Hyon Song-wol, so publicly identified with Kim Jong-un, had attracted the jealous ire of Kim’s wife.

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“There is a political reason behind this,” he said. “Or, as Kim’s wife once belonged to the same group, it is possible that these executions are more about Kim’s wife.”

Reports of the execution clashed strangely with news that not only is Pyongyang busy mending the bridges with the South that it had deliberately blown up earlier this year, but that it is also hoping to open the country to an unprecedented wave of foreign tourists.

In April, reacting furiously to the annual military exercises staged by the US and South Korea, the North Koreans pulled their 53,000-strong workforce from the Kaesong industrial complex where around 100 South Korean firms had been producing textiles and electronic goods with North Korean labour since 2004. A dry run for an intended gradual rapprochement between the two countries, Kaesong remained unique and dependent on subsidies from Seoul, which provided the electricity and water the plants required, and two square meals a day for the workers. Of the $140 paid per worker per month, the Pyongyang regime took a large chunk.

Despite obtaining no concessions from the South from its torrent of threats and menaces, Pyongyang has now, after seven rounds of talks with the South, agreed to reopen the complex. It has also agreed to resume the temporary reunions of families separated by the division of the peninsula ever since the end of the Korean War, after a suspension lasting three years, and to once again allow holidaymakers from the South to visit the resort of Mt Kumgang, which is barred to ordinary North Koreans. Visits to the area were abruptly cancelled in 2008 after a North Korean soldier shot dead a tourist on the beach.

More ambitious are the efforts announced this week to attract tourists from much farther afield. Announcing plans for flights to Pyongyang from China, South-east Asia and Europe, North Korea’s tourism tsar, Jo Song-gyu, told the state news agency, “Abundant in tourism resources, [North Korea] has a bright future to develop tourism.” He added that hotels were being refurbished to international standards, and duty-free shops and fitness centres were being constructed.

Until now the small numbers of Western tourists coming to the country have been closely watched and rigidly controlled to prevent them having unrehearsed encounters with ordinary North Koreans. If Pyongyang is now contemplating accepting much larger numbers – inherently harder to control – the nation’s need for hard currency must be getting desperate.