CNN reports that a North Korean diplomat a South Korean newspaper said had been executed by firing squad is alive and in state custody.

The American media outlet said on Tuesday that according to several sources familiar with the situation, North Korea's special envoy to the United States, Kim Hyok-chol, is being investigated for his role in the failed Hanoi summit between U.S. President Donald Trump and North Korean leader Kim Jong-un in February.

One source said that Kim Hyok-chol's fate had not been determined but that he could still face "heavy punishment."

The report said Kim Yong-chol, one of North Korea's most senior officials, reportedly has seen his power "almost deprived" since the Hanoi summit, despite his public appearance alongside the North Korean leader over the weekend. 

Sources also said Kim Jong-un's translator in Hanoi, Sin Hye-yong, is also in custody and under investigation.