A man accused of leading a group that blackmailed girls into sharing sexual videos – which were then shared in pay-to-view chatrooms – has been named after an outcry in South Korea.
At least 10,000 people used the chatrooms, with some paying up to $1,200 [£1,000] for access.
Some 74 people, including 16 underage girls, were exploited.
A police committee took the unusual step of naming Cho Ju-bin, 24, after five million people signed petitions.
“I apologise to those who were hurt by me,” Cho said as he was led away from a Seoul police station on Wednesday.
“Thank you for putting a brake on the life of a devil that could not be stopped.”
He did not respond when reporters asked if he admitted the charges.
He is accused of abuse, threats, and coercion, and of violating the child protection act, the privacy act and the sexual abuse act.
Customers paid to access the so-called “nth rooms”, where extorted content from underage girls was uploaded in real time. Fees ranged from $200 to $1,200.
According to Korean outlet Kookmin Ilbo, each of the eight “nth rooms” hosted videos from three to four girls who had been blackmailed by chatroom operators.
The girls were often runaways who were active on chat apps, or Twitter, and engaged in prostitution or sexting for money.
The chatroom operators contacted the girls, promising modelling or escort jobs.
They were then directed to a Telegram account where the operator extracted their names, phone numbers, addresses, friend lists, and photos, which were then used to blackmail them.
One school girl – speaking to Kim Hyun Jung on South Korea’s CBS radio – said she was approached online after looking for work.
After being promised money and a phone, she was told to send pictures of herself, followed by sexual abuse videos.
The victim said there were at least 40 videos in total.
“He already had my face, my voice, my personal information,” the victim said.
“I was afraid that he would threaten me with that information if I said I would quit.”
Details emerged via a newspaper report in November, followed by another report in March.
The story caused outrage in a country where another abuse scandal – the Burning Sun case – dominated headlines last year.
A petition on the presidential website, calling for the main suspect to be named, was signed 2.6m times.
Another petition on the same site, calling for all chatroom users to be named, was signed almost 2m times.
President Moon Jae-in regarded the chatrooms as a “cruel act that destroyed lives”, according to a spokesman.
“The fact that more than three million people signed the petition…is a serious plea to the government from the people, especially women, requesting a stop to such malicious digital sex crimes,” the spokesman added.
The National Police Agency told reporters that 124 suspects had been arrested – with 18 chat room operators in custody – since September. Cho is one of the 18.
A user called GodGod, who is suspected of first creating the chat room, remains at large.
“Through strict investigation, the police will entirely transform the social apathy to digital sex crime and strongly root out such crime from our society,” said Min Gap-ryong, commissioner general of the Korean National Police Agency.