SEOUL, South Korea (AP) — South Korean prosecutors on Wednesday began reviewing whether to formally charge a man arrested last week on allegations that he operated secret chatrooms where he posted sexually abusive videos of blackmailed women in return for cryptocurrency payments.

The allegations have triggered intense public uproar and soul-searching over a culture that critics say is lenient about sexual violence and continuously fails the victims, prompting President Moon Jae-in to call for thorough investigation and stern punishment for operators of such chatrooms and their users.

Wearing a neck brace and handcuffed to his waist, the suspect, Cho Ju-bin, 24, was paraded before journalists at the Jongno Police Station in Seoul before officers drove him to the prosecutors’ office. Police officers created a perimeter around the station’s gate to block off angry protesters, who waved signs that read “From chatroom to prison” and “Punish all users” and yelled “Give him the highest penalty!”

“Thank you for stopping the life of a devil (I) couldn’t stop,” Cho said in front of a barrage of camera flashes.

He refused to answer questions about the accusations against him but offered apologies to a former mayor of Gwangju City, the president of local broadcaster JTBC and a freelance journalist currently on trial for allegedly attempting to blackmail the JTBC president for reasons that weren’t immediately clear. Police said they currently don’t have any knowledge linking the three men with the chatrooms.

JTBC later said that its president, Sohn Suk-hee, had been blackmailed by Cho, who claimed to have been paid by the freelance journalist to harm him or his family. JTBC said Sohn paid Cho an unspecified amount of money, but didn’t say when the payment was made.

Before sending Cho’s case to prosecutors, police said they had arrested 18 people since September while investigating private chatrooms on the Telegram messaging app, where users paid in cryptocurrency to view videos of a sexual nature that involved dozens of allegedly blackmailed women and girls.

Under the nickname “The Doctor,” Cho allegedly operated one of the biggest chatrooms, with around 10,000 users, and police are investigating whether he operated others. He is suspected of using private information he secured from workers at local government offices to blackmail victims lured through fake job ads, forcing them to create sexually explicit videos that sometimes involved rape and violence.

Police, who seized about 130 million won ($105,000) in cash from Cho’s house following his arrest last week, said his customers could have paid as much as 1.5 million won ($1,200) in cryptocurrency to watch the videos.

While police usually don’t release the identities of criminal suspects out of respect of their rights, they made an exception with Cho by revealing his full name and displaying him in front of the media, saying that his alleged crime was particularly heinous.

Police are chasing other chatroom operators, including a Telegram user who used the nickname “GodGod.”

Amid heightened public attention, prosecutors launched an unusually large 21-member task force to investigate Cho’s case and other chatrooms. They have as much as 20 days to investigate Cho before indicting him in court, the Seoul Central District Prosecutors’ Office said.

Police and prosecution officials said it wasn't clear how much chatroom operators profited from the videos. Civic activists have speculated that the chatrooms could have garnered as much as 260,000 paid customers, including overlapping members in different chatrooms.

Nearly 6 million people have signed online petitions filed to Moon's presidential office calling for the disclosure of personal information of all chatroom operators and customers and for their stern punishment.

On Monday, Moon called for a thorough investigation and denounced the alleged crimes as a “cruel act destroying a human’s life.”

South Korea for years has struggled to deal with what the government describes as “digital sex crimes,” which aside from the abusive chatrooms also include the spread of intimate photos and videos taken by smartphones or tiny spy cameras hidden in public spaces and buildings, an issue that triggered massive protests in 2018.

The Justice Ministry issued an apology over what it described as a years-long failure by the legal system to properly respond to such crimes and said it would “employ all possible efforts” to fully track down the chatroom operators and users, ensure stern punishment and reclaim any financial gains from the videos.