Cho Joo-bin was sentenced to 40 years in a South Korean prison for sexual exploitation

Police eventually tracked down Mr. Cho, and when he was arrested in March, his identity was concealed from the public, in his usual policy of protecting the identities of the suspects, respecting his own rights and those of their relatives. But millions of South Koreans joined an online petition asking the government to disclose its name and image and identify all customers of the online chat rooms operated by Mr. Cho and others.

Eventually, police made his name public and allowed the press to photograph him, saying they made an exception because he had been charged with particularly horrific crimes.

After his arrest, Mr. Cho told reporters, “Thank you for stopping my life as a devil that I couldn’t stop. During his trial, he acknowledged most of the charges but denied blackmailing the women. He has a week to appeal Thursday’s decision.

According to local news, several customers turned to the police and one killed himself. In August, a 26-year-old man was sentenced to two years in prison on charges of gaining access to the personal data of women in the database while working in a government office, which he then sold to Mr. Cho. On Thursday, Mr. Cho’s accomplices were sentenced to between five and 15 years in prison. Two clients who paid to view the express footage were sentenced to eight and seven years in prison.

In recent years, South Korean police have begun taking action against sexually explicit file-sharing websites as part of an international effort against child pornography. They said they soon realized that much of the illegal pornography trade was moving to online chat rooms through messaging services like Telegram. Since then, dozens of people have been arrested in 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 pseudonym “The Watchman”.

Amid talks around the #MeToo movement, Seoul’s popular mayor, Park Won-soon, killed himself in July after one of his secretaries went to the police and accused him of sexual harassment.

In 2017, South Korea revised its laws to strengthen the punishment for spycam pornography – the use of tiny, hidden cameras to film female victims, often in public bathrooms. After Mr. Cho’s fame went up, President Moon Jae-in promised a full investigation and severe punishment against online chat room operators and customers.