Last year, a YouTuber accused Kim Soo-hyun, one of South Korea’s best-known actors, of dating an actress when she was still a minor. He denied the claim but his career rapidly derailed, reflecting the unforgiving scrutiny celebrities can face in South Korea.

On Tuesday, the police arrested the YouTuber, Kim Se-ui, on charges including spreading false information. He is accused of doctoring text messages and fabricating an audio recording using artificial intelligence to defame the actor.

Mr. Kim, who is known for publishing sensational and gossip-driven content about celebrities and politicians on his YouTube channel, Hover Lab, denies the charges.

Representatives for Mr. Kim, the actor, said he had been vindicated. “At last, the truth has been proven,” his agency, Gold Medalist, said in a statement on Wednesday.

The actor got embroiled in the controversy after the actress Kim Sae-ron, who became famous as a child, and whom he had once dated, was found dead last February.

Her career had suffered for years after she was caught driving under the influence in 2022. The police ruled her death a suicide. That ignited intense scrutiny into her personal life, including rumors surrounding her romantic relationship with Mr. Kim, who is known for playing the alien lead in the melodrama “My Love from the Star” and a North Korean spy in “Secretly, Greatly.”

He faced immense backlash after Hover Lab published what it said were text messages exchanged by the couple when Ms. Kim was 15 and Mr. Kim was 28, and an audio recording in which she said that Mr. Kim had started dating her when she was in middle school. It also accused Mr. Kim of sexually grooming Ms. Kim when she was a minor, and ignoring her when she was in financial trouble.

At the time, Hover Lab said that it had obtained some of the information from Ms. Kim’s family. A lawyer for the family, whose role in the case is unclear, did not immediately respond to a request for comment on Thursday.

Mr. Kim, the actor, had filed defamation cases against the family and the YouTuber.

Before entering the court on Tuesday, Mr. Kim, the YouTuber, told reporters that he denied any wrongdoing and said that the audio recording had been verified by the National Forensic Service, a government agency, as authentic.

“The arrest warrant is clearly based on falsities,” he said. The forensic service referred a request for comment to the Gangnam Police Station, which is investigating the matter. The police did not immediately respond to a request for comment.

Mr. Kim, the actor, denied the accusations against him at an emotional news conference in March 2025.

“I can’t admit to something I didn’t do,” he said. “I did not date the deceased when she was a minor.”

Since then, he has not appeared in any new shows or modeling gigs in South Korea.