South Korean leader of online sexual blackmail ring sentenced to 40 years

Cho Joo-bin walks out of a police station in Seoul, South Korea, on March 25.

(CNN)The South Korean leader of an online sexual blackmail ring that targeted minors and young women was sentenced to 40 years in jail on Thursday, marking the end of an explosive criminal case that sparked outrage across the country.

Cho Joo-bin, 25, hosted online rooms on encrypted messaging app Telegram, where users paid to see young girls perform sexual acts under coercion. At least 74 victims, including 16 minors, were blackmailed into uploading explicit images onto the group chats. At least 10,000 people used the chat rooms, with some paying up to $1,200 for access, officials say
After two university journalism students discovered the Telegram groups last summer, police launched their investigation, and arrested Cho in March.
    He was later indicted under 15 charges of 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 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).
      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.
        After passing the verdict, the judge, Lee Hyun-woo, explained that Cho had no criminal record and "has made some agreements with some victims." However, Cho had "created an organization structure" victimizing women, and profited off their exploitation.
        "He revealed the personal information of the victims and by doing so not only caused damage, but by distributing this repeatedly caused recurring damage to victims," said the judge. "His behaviors caused extreme pain on the victims and they are demanding severe punishment."
        "Considering the seriousness and meticulous plotting of the crimes, the number victims and damage on victims, social harm caused by the crime, and the attitude of the defendant, it is necessary to isolate the defendant from society for a long time."
        Police arrested more than 120 people connected to the chat groups in March. Several of Cho's collaborators were also charged and indicted; five others received sentences on Thursday, ranging from seven to 15 years.
        One collaborator, a minor identified only by his surname Lee, was sentenced to a juvenile facility for a minimum of 5 years and a maximum of 10 years.
        Cho's verdict received mixed results from the public, with some praising the decision and others arguing he should have received a life sentence.
        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."

        'My daily scars seem to be endless'

        Before Thursday's sentencing, Cho Joo-bin and several victims last testified at a trial on October 22, where the victims described the exploitation they faced and the trauma that remained.