South Korean police are seeking an arrest warrant for a YouTuber who allegedly faked evidence that defamed actor Kim Soo-hyun and fuelled a scandal which ended his career.

Authorities say the YouTuber had manipulated screenshots of text messages and shared an audio file made with AI to give the impression that the actor had dated actress Kim Sae-ron when she was still a minor.

The allegations surfaced last year, shortly after Kim Sae-ron killed herself at the age of 24.

The scandal shook the country and upended the career of Kim Soo-hyun, who is a household name in South Korea. The actor has consistently denied the allegations.

The YouTuber, Kim Se-ui, has since posted a video claiming the authorities' allegations were a "subterfuge meant to disrupt his investigation".

Months after Kim Sae-ron's death, the YouTuber had posted online a voice recording in which the actress could be heard saying she had been dating Kim Soo-hyun since she was in middle school.

The YouTuber Kim Se-ui, who has nearly a million followers on his channel, had also presented screenshots of text messages purportedly sent between the actor and the actress.

Authorities now say that the voice recording was generated by AI.

They also allege that the YouTuber had manipulated screenshots of text messages sent from the actress's phone to make it look like she had been texting Kim Soo-hyun.

The YouTuber had knowingly spread the false claims for financial gain, authorities say.

His actions "collapsed Kim Soo-hyun's social base and his economic activities across the board, and destroyed the basis for his professional survival," according to a police filing reported by news outlet JoongAng Ilbo.

Police also say Kim Soo-hyun is "still receiving psychiatric treatment".

Celebrities in South Korea are held to high standards and put under extreme scrutiny. Besides serious allegations of sexual assault, celebrities have been forced to vanish from the public eye for being exposed as teenage bullies or wearing fake designer clothes.

Kim Sae-ron herself was a victim of online hate by fans after she was fined for a 2022 drink-driving incident. Prior to that, she had been seen as one of the most promising young actresses in South Korea.

Soon after her death, rumours surfaced online alleging that Kim Soo-hyun dated her when she was just 15 years old. These gained traction after the YouTuber posted the texts and audio, and the actress' family publicly backed him up.

Kim Soo-hyun's agency initially denied the couple had ever dated.

The actor later admitted he had in fact dated the actress for a year - but only when she was an adult.

At a tearful press conference in March 2025, the actor insisted they had never dated while she was underage. "I can't admit to something I didn't do," he said.

That month, he filed criminal complaints and lawsuits against the YouTuber and the actress' family for making false accusations.

Since then Kim Soo-hyun - who once starred in multiple hit TV shows and advertisements - has not made any official public appearances.

The release of Knock-Off, a Disney+ series he had been working on when the scandal broke, has been indefinitely postponed.

Kim Soo-hyun and his agency have not yet commented on the authorities' application for an arrest warrant on the YouTuber.