Cho Joo-bin Gets 40 Years in South Korean Prison for Sexual Exploitation

The police eventually tracked Mr. Cho down, and when he was arrested in March, they kept his identity from the public, in its usual policy of protecting criminal suspects’ identities to respect their rights and that of their relatives. But millions of South Koreans joined an online petition asking the government to reveal his name and image and to identify all customers of online chat rooms operated by Mr. Cho and others like him.

Eventually, the police revealed his name and allowed news outlets to take pictures of him, saying that they had made an exception because he had been charged with particularly heinous crimes.

After he was arrested, Mr. Cho told reporters, “Thank you for stopping my life as a devil that I could not stop.” During his trial, he admitted to most of the charges but denied blackmailing the women. He has a week to appeal Thursday’s ruling.

Several customers have turned themselves in to the police, and one killed himself, according to local news reports. In August, a 26-year-old man was sentenced to two years in prison on charges of gaining access to the personal information on women in a database while he worked in a government office that he then sold to Mr. Cho. On Thursday, three of Mr. Cho’s accomplices received sentences of between five and 15 years in prison. Two customers who paid to watch the explicit footage were sentenced to eight and seven years in prison.

In recent years, the South Korean police began cracking down on sexually explicit file-sharing websites as part of international efforts to fight child pornography. They said they soon realized that much of the illegal trade in pornography was migrating to online chat rooms on messaging services like Telegram. They have since arrested dozens of people involved in the operations. This month, a 38-year-old former office worker was sentenced to seven years in prison on charges of running similar chat rooms under the alias “The Watchman.”

Amid conversations around the #MeToo movement, ​ the widely popular mayor of Seoul, Park Won-soon, killed himself in July after one of his secretaries went to the police, accusing him of sexual harassment.

In 2017, South Korea revised laws to strengthen punishment for spycam pornography — the use of tiny, hidden cameras to film female victims, often in public bathrooms. After Mr. Cho’s case made headlines, President Moon Jae-in promised a full investigation and stern punishment against operators and customers of the online ​chat rooms​.