A man suspected of blackmailing dozens of victims, including minors, into performing violent sex acts and selling the videos in mobile chat rooms was handed over to the prosecution on Wednesday for further investigation.

At least 74 people, including 16 underage girls, are known to have been exploited in the case, widely known as the "Nth room case," in which prime suspect Cho Ju-bin allegedly lured victims into taking photos and later coerced them into performing more gruesome sex acts.

Police have so far apprehended 126 in relation to the case.

Nineteen, including Cho, have been formally detained.

The Seoul Metropolitan Police Agency sent Cho's case to the Seoul Central District Prosecutors Office on charges including violation of the act on the protection of children and youth against sex offenses.

The 24-year-old, whose name and photo were released on Tuesday, appeared in front of the public early Wednesday as he was being transferred to the prosecution from a detention unit at Jongno Police Station in central Seoul.

"I genuinely apologize to everyone who has suffered harm because of me, including President Sohn Suk-hee, Mayor Yoon Jang-hyeon and journalist Kim Woong," said Cho, who was wearing a neck protector and a bandage.

It is not clear why he mentioned the names of the three men.

Sohn is a president at South Korean cable broadcaster JTBC, and Yoon is a former mayor of the southwestern city of Gwangju. Kim is a freelance journalist embroiled in a legal fight with Sohn over a car accident.

Police confirmed the three are irrelevant in the sex abuse case, saying they are looking into possibilities they may be victims of separate fraud cases involving Cho.

JTBC confirmed that Sohn was approached by Cho, who claimed to have been paid by Kim to harm Sohn and his family. The former news anchor paid Cho in the process of verifying Cho's claim, the company said, without specifying the amount.

"Thank you for putting a brake on the life of a devil that could not be stopped," he added. He did not, however, respond to questions on whether he acknowledges the charges and whether he feels remorse for his alleged actions.

Outside the police station, some people shouted at him, telling him to suffer in pain and urging authorities to give him the heaviest legal punishment possible.

The scandal, which has become notorious for its extreme brutality, has shocked the nation and prompted an outpouring of grief and rage.

More than 5 million signed petitions at an online platform run by the presidential office and shared hashtags, urging authorities to disclose all members of the chat rooms and punish them strongly.

An estimated 260,000 people, including overlapping members in different chat rooms, are known to have joined these mobile chat rooms on messaging services, such as Telegram and Discord.

President Moon Jae-in has vowed to take a stern approach in combating digital sex crimes, which have evolved on the back of technological developments and the often anonymous user environment on digital platforms.

He described the acts of the offenders as "cruel" behavior that destroyed the lives of victims and said he "feels sympathetic" to the "justifiable" public fury over it, his office said Monday.

Investigative authorities have declared an all-out fight.

On Wednesday, the police launched a special unit focusing on digital sex crimes to strengthen cooperation with overseas law enforcement authorities and technology companies to better track down perpetrators.

The prosecution also set up a 21-member task force with investigators from teams that specialize in child and youth crimes and recovering illegally obtained gains from criminals.

Cho reportedly reaped hundreds of millions of won in cryptocurrencies by charging as much as 1.5 million won ($1,213) for some of the exploitative content. (Yonhap)