Seoul, Oct 14 : South Korea's Supreme Court on Thursday approved a 42-year prison sentence for Cho Ju-bin, the mastermind of a notorious online sex blackmail ring. The top court also confirmed lower courts' order that Cho has to wear an electronic bracelet for 30 years, pay a forfeiture of 100 million won ($90,000), be banned from working at children-related facilities for 10 years after his release and his personal details be made public for 10 years, reports Yonhap News Agency. Cho was indicted in April last year for organising the criminal ring together with 38 accomplices, blackmailing 74 minor and adult victims into filming pornographic content, and distributing the sex abuse materials to members of a pay-to-view Telegram chat room, called Baksabang. The 25-year-old man was also charged with hiding about 108 million won in criminal proceeds. Cho committed his online sexual offenses from March 2019 to February 2020 before being arrested by police on March 16, 2020. A district court sentenced him to 45 years behind bars but an appellate court lowered his prison sentence to 42 years. Cho, while admitting to the charges of producing and distributing sex abuse materials, claimed that Baksabang was not a criminal ring and some evidence from the prosecution was illegally collected. But the Supreme Court dismissed his appeal. The nation was shocked by a string of sexual exploitation cases centred on group chat rooms of the Telegram messenger service, including Baksabang, last year, prompting the government to announce get-tough measures against digital sex crimes. Law enforcement authorities have since vowed to punish even buyers, advertisers and possessors of child and youth sexual abuse materials, as well as their producers and sellers, and treat any production of digital sexual materials as a felony crime. /IANS