The founder of the world’s largest online child pornography website, which utilized the darknet and cryptocurrency in its criminal operations, has been arrested, the Justice Department announced Wednesday.

Jong Woo Son, 23, the administrator of the child porn website Welcome To Video, was arrested in March 2018, and the DOJ said it spent a year and a half following his arrest investigating the site’s users and shutting down its online operations.

The South Korean was arrested along with 337 website users in the United States and globally by a joint operation including U.S., British, and South Korean authorities.

Authorities seized the website's server with approximately eight terabytes of child sexual exploitation videos, making it “one of the largest seizures of its kind.” The server showed the website, partially concealed on hidden online networks known as the darknet, had more than a million bitcoin addresses, which signified that it could have that many users.

Welcome To Video was among the first where users could buy child exploitation videos using the virtual cryptocurrency bitcoin, authorities said. The site’s upload page stated “Do not upload adult porn” with the last two words bolded, and DOJ said the website “boasted over one million downloads of child exploitation videos by users.”

The files seized from the child porn website contained over 250,000 unique videos, nearly half of which so far had not been previously known to exist, and the images are still being analyzed by the National Center for Missing and Exploited Children. Some of the images are described in the criminal complaint and are graphic, violent, abusive, and disturbing.

DOJ said its investigation resulted in criminal referral leads sent to 38 countries, and at least 23 minor victims in the U.S., Spain, and the United Kingdom “who were being actively abused by the users of the site” were rescued because of the operation.

A forfeiture complaint against 24 cryptocurrency accounts used in connection to the child porn website was also unsealed Wednesday. DOJ said the virtual currency accounts were allegedly used by 24 people in five countries “to fund the website and promote the exploitation of children.”

The more than 300 people arrested — who gained access to the website either by uploading child pornography, referring new users to the site, or paying for access using bitcoin or other forms of cryptocurrency — were from two dozen states in the U.S., as well as from Australia, Brazil, Canada, the Czech Republic, Germany, Ireland, Saudi Arabia, South Korea, Spain, the United Arab Emirates, and the U.K.

DOJ searched the homes and businesses of 92 people in the U.S. tied to this child exploitation scheme. In just the Washington, D.C., area alone, DOJ said five search warrants were executed, and eight people who conspired with the website’s administrator and used the site themselves were arrested and that two users of the website died by suicide after these searches were carried out.

