SEOUL, South Korea (AP) — A man claiming to be the son of the slain half brother of North Korean leader Kim Jong Un has appeared in a YouTube video saying he’s safely with his mother and sister.

Kim Jong Nam was killed by two women who rubbed a prohibited nerve agent on his face at an airport in Malaysia on Feb. 13, according to Malaysian police. Kim Jong Un was widely suspected to be behind his brother’s murder to eliminate a potential challenger to his rule. Subsequently, there have been worries about the safety of Kim Jong Nam’s son Kim Han Sol, who described his uncle Kim Jong Un as a “dictator” during a rare 2012 interview with Finnish television.

“My name is Kim Han Sol from North Korea, part of the Kim family,” the man says in English in the 40-second YouTube clip uploaded Wednesday. “My father has been killed a few days ago. I’m currently with my mother and my sister. … We hope this gets better soon.”

An official at South Korea’s National Intelligence Service said the NIS had determined that the man in the video is Kim Han Sol. The public affairs official, who spoke on condition of anonymity, citing department rules, didn’t explain how his agency confirmed the man’s identity.

NIS officials gave the same confirmation to the office of a lawmaker who sits on South Korea’s intelligence committee without saying how it reached such a conclusion, according to an aide to the lawmaker. The aide requested anonymity for both himself and the lawmaker, saying they weren’t authorized to give the information to the press.

The NIS has a spotty record on reporting developments in North Korea. But a private voice analysis institute in Seoul said there was a “high probability” that Kim Han Sol in the 2012 interview, which can also be found on YouTube, and the man in the latest video clip were the same speaker.

“It’s right to determine they are the same person,” said Lee Cheul-houng, head of the Transcription Analysis Laboratory.

The man in the latest video doesn’t talk about the whereabouts of his family or how they were being protected. The video was posted on the YouTube channel of Cheollima Civil Defense, which describes itself as a group helping North Korean defectors.

The group said on its website that it responded to an “emergency request” last month by three members of Kim Jong Nam’s family and relocated them to safety. The group expressed gratitude to the Netherlands, China, the United States and a “fourth government to remain unnamed” for providing assistance in protecting the three.

South Korea’s Unification Ministry said it had no knowledge of the Cheollima group.

Malaysia has never directly accused North Korea of killing Kim Jong Nam, though it is searching for seven North Korean suspects over the case. North Korea has denied any responsibility and accused South Korea of being behind the accusation.

The investigation into Kim’s death has created a diplomatic battle between Malaysia and North Korea, which have banned each other’s citizens from leaving their respective countries.