CNN  — 

The North Korean diplomat who South Korea’s largest newspaper said had been executed by firing squad is alive and in state custody, 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 that took place between United States President Donald Trump and North Korean leader Kim Jong Un in February, the sources said.

That meeting, the second between the two leaders, ended abruptly without the two sides reaching a deal.

Kim Jong Un’s translator in Hanoi, Sin Hye Yong, also is in custody and under investigation, sources said.

Kim Hyok Chol, North Korea's special representative for US affairs, leaves the Government Guesthouse in Hanoi on February 23.

South Korean newspaper Chosun Ilbo reported Friday that Kim Yong Chol, one of North Korea’s most senior officials who had sat in the White House across from President Trump for talks little more than a year ago, had been purged and that Kim Hyok Chol had been executed by firing squad as punishment for the lack of success in Hanoi.

The story cited an anonymous source inside North Korea, and was not confirmed by the governments of North or South Korea. US Secretary of State Mike Pompeo said his country was looking into the reports, while South Korea’s Presidential Blue House said it was not appropriate “to make any hasty judgment or comment about that part.”

At a news conference Tuesday, South Korea’s Unification Minister, Kim Yeon-chul, declined to discuss either Chosun Ilbo or CNN’s reporting on the whereabouts of the North Korean officials.

The report’s veracity was called into question Sunday after North Korean state media reported that Kim Yong Chol attended an art performance alongside Kim Jong Un. An invitation to join to join the North Korean leader in public would likely not be extended to someone who had fallen out of favor.

US Secretary of State Mike Pompeo (left) speaks with North Korean senior ruling party official Kim Yong Chol during the second US-North Korea summit at the Sofitel Legend Metropole hotel in Hanoi on February 28.

When asked about the Chosun Ilbo report, one of the sources who spoke to CNN said, “the news was wrong.”

The sources said Kim Yong Chol had seen power “almost deprived” since the Hanoi summit, despite his public appearance alongside the North Korean leader over the weekend.

The sources add Kim, who previously served as North Korea’s spy chief, was not sentenced to forced labor, but instead “kept silently in his office writing statements of self-criticism.”

Trotting him out publicly was a signal to Washington that the North Korean leader was “not breaking off negotiations over denuclearization,” despite escalating tensions in recent weeks, one source said. North Korea test-fired short-range ballistic missiles last month, worrying many of the country’s neighbors. They were the first tests of their kind since 2017.

The fate of Kim Hyok Chol, the special envoy, had not been determined, but he could still face “heavy punishment,” one of the sources said.

Kim Song Hye, a North Korean official on the team negotiating with the United States, is also in custody and under investigation, sources said.

The individuals who spoke to CNN requested anonymity because they were not authorized to publicly speak about the situation.

Chosun’s story on the purported punishments for Kim Hyok Chol and Kim Yong Chol was widely circulated but met with heavy skepticism from experts due to its thin sourcing. If true, it would have amounted to a rapid downfall for two of North Korea’s highest profile figures.

Analysts had speculated that some of the North Korean diplomats overseeing the US negotiations in Hanoi were in hot water after the latest round of talks between the two countries ended abruptly in Vietnam without an agreement.

Diplomats and officials from Pyongyang have been known to disappear from public view only to resurface after a period of so-called reeducation, analysts and former diplomats say. Kim Yong Ju, the brother of Kim Il Sung – North Korea’s founder and the grandfather of Kim Jong Un – disappeared for nearly two decades. He disappeared in the mid 1970s and then reappeared in 1993.

Correction: A previous version of this story misidentified Kim Song Hye as Kim Jong Un's translator.

CNN’s Joshua Berlinger and Yoonjung Seo contributed to this report