Hyon was among a dozen well-known performers arrested August 17 for violating laws against pornography. Mun Kyong-jin, head of the Unhasu Orchestra was arrested along with other orchestra members, as well as performers with the Wangjaesan Light Music Band.
They were reportedly accused of recording themselves having sex and selling the videos, which made it as far as China.
"They were executed with machine guns while the key members of the Unhasu Orchestra, Wangjaesan Light Band and Moranbong Band as well as the families of the victims looked on." Guilty by association, the families of the executed have reportedly been sent to prison camps.
“Kim Jong Un has been viciously eliminating anyone who he deems a challenge to his authority,” the source told South Korea's Chosun Ilbo.
Hyon was a singer with the Pochonbo Electronic Ensemble, one of North Korea's most popular bands, famous for revolutionary and propaganda songs.
Kim met Hyon about a decade ago, when they were teenagers. The pair dated, but Kim was allegedly ordered by his father Kim Jong-il to end the relationship. Since that time, rumors have circulated that the two were having an affair.
Hyon ultimately married a soldier. Kim's wife, Ri Sol-ju, was also a member of the Unhasu Orchestra before she married him.
Whether Kim's wife had any say in the executions is unclear. The Unhasu Orchestra and Wangjaesan Light Music Band have reportedly been disbanded.