Police nabbed a 20-something man for allegedly subjecting at least 74 people, including 16 minors, to sexual exploitation and assault and operating a pornography ring on Telegram, the police revealed Friday.

The alleged crimes involved the messenger service Telegram, where videos of a sexual nature were posted in return for cryptocurrency payments.

The suspect, currently known by the surname Cho and by the Telegram nickname “doctor,” is thought to be one of a large number of individuals who used the service to sell illegal video content. Cho and others are accused of blackmailing women and minors into creating videos of a sexual nature and selling the materials to Telegram users. Some of the videos, distributed through several different Telegram chat rooms, showed victims carving the word “slave” on their bodies.

According to the police, the suspect victimized women and minors between December 2018 and earlier this month. The police confiscated 130 million won ($104,430) from the suspect’s home and are currently tracking the assets he is alleged to have gained through criminal activities.

Cho is also suspected of securing private information about the victims and chat room members through administrative aides at local government offices to blackmail the users and victims.

The police suspect that Cho operated a number of chat rooms, charging users between 200,000 won and 1.5 million won for access.

According to the police, some of the chat rooms had as many as 10,000 users. Cho also recruited some of the users for criminal activities including money laundering, police said, and some of his alleged accomplices sexually assaulted some of the victims. Cho’s chat rooms and others of a similar nature are thought to have been used by more than 200,000 people. So far, 13 of Cho’s alleged accomplices have been apprehended, and four have been arrested and referred to the prosecution.

The suspects, whose average age is around 24 or 25, include a number of minors, the police said. According to the police, Cho kept his identity hidden from his accomplices. Cho had denied the allegations, but has since confessed to his crimes, they said. The police are also tracking users of the chat rooms in question, and plan to bring charges against them.

The police said they will decide sometime next week whether to disclose Cho’s full identity. Nearly 300,000 people signed a petition in less than two days urging them to do so.

By Choi He-suk (cheesuk@heraldcorp.com)