SEOUL, Nov. 27 (CGTN) - A South Korean court on Thursday sentenced the leader of an online sexual blackmail ring to 40 years in prison, Yonhap news agency reported.

Cho Ju-bin, 24, was found guilty of running an online network that blackmailed at least 74 women, including 16 teenagers, into what authorities called "virtual enslavement" by forcing them to send increasingly degrading and sometimes violent sexual imagery of themselves between May 2019 and February 2020.

"The defendant had lured and threatened multiple victims in various ways to produce pornography and distributed it for a long time to many," Yonhap reported, citing an unidentified judge who handed down the verdict and sentence. "He in particular inflicted irrecoverable damage to many victims by publishing their identifies."

The Seoul Central District Court sentenced Cho for producing and distributing illegal sexual visual material, forced sexual abuse, rape, sexual harassment, blackmailing, recording sexually abusive behaviors, coercion, violation of private information protection, and fraud.

He was also found guilty of "instructing a third party to directly rape a victim, who was a minor," the judge ruled.

Cho's sentence, passed down in the Seoul Central District Court, also included the wearing of an electronic ankle bracelet for 30 years and a fine of 10.64 million Korean won (about 9,600 U.S. dollars).

Prosecutors had requested life imprisonment, arguing in court that his crime was "unprecedented in history," and that Cho had "insulted and abhorred" victims without remorse.

The so-called "Nth room" is an online chat room on encrypted messaging app Telegram, where users paid to see young girls perform sexual acts under coercion. Victims, including 16 teenagers, were blackmailed into uploading explicit images onto the group chats. At least 10,000 people used the chat rooms, with some paying up to 1.5 million won (1,360 U.S. dollars) for access, officials say.

Cho, one of the many operators of the "Nth room," recruited his victims through posting fake modeling posts online. The applicants would send their photos along with their names, address, and Social Security numbers to get paid. Then Cho would request for more revealing photos from the young girls and then use them as blackmail material.

Members of "Nth room" pay by bitcoins, so their payment methods would be difficult to trace down.

Last summer, two university journalism students discovered the Telegram groups, some of which had over 9,000 members at any one time. Later, the police launched their investigation, and arrested more than 120 people connected to the chat groups in March, including Cho.

Several of Cho's collaborators were also charged and indicted; five others received sentences on Thursday, ranging from seven to 15 years.

The case sparked a national outcry, with millions of Koreans signing petitions urging authorities to release Cho's identity and investigate not only the organizers, but also participants of the network.

South Korea usually protects criminal suspects' identities to respect their rights and that of their relatives.

Lee Hyo-rin, an activist in a coalition of non-profit organizations, called the verdict a chance to reflect on lenient rulings in previous digital sex crimes.

"In the past, digital sex crimes in South Korea have received weak punishments, and therefore criticism toward the justice system was high," Lee said. "There are similar crimes ongoing in the country and I hope this ruling will offer guidance to levy serious punishment on possible future digital sex crimes."

Nevertheless, the victims of "Nth room" are still struggling to return to normal life after the exploitation and the trauma they experienced.

"Due to personal information and sexual exploitation video, it is difficult to live a daily life. I'm so busy deleting videos distributed by Cho Ju-bin that my daily scars seem to be endless no matter what treatment I receive. Just as my wounds are endless, I hope Cho's punishment is endless," one of the victims said anonymously in a statement read by their attorney in court.