The investigation sprang from the takedown in October of South Korea-based site Welcome to Video, which U.S. authorities described as one of the world’s largest child pornography websites. Investigators following its trail found that a District man who admitted to downloading nearly 3,000 videos from that site also allegedly used DarkScandals, authorities said.

A nine-count indictment returned March 5 and unsealed Thursday charges Mohammad with distributing child pornography, producing and transporting obscene matters for sale or distribution and engaging in its sale and transfer, and money laundering.

“The types of crimes described in this indictment are the most disgusting I’ve encountered in 30 years of law enforcement,” Don Fort, chief of IRS Criminal Investigation, said in a statement, adding: “It is a special kind of evil to prey on and profit from the pain of others. Criminals should know if you leave a digital footprint, we will find you.”

Mohammad was arrested Monday at his home in the Netherlands, where he has been charged with possession and distribution of child abuse material, sedition and tax offenses, Dutch authorities said. An attorney for Mohammad could not immediately be reached for comment.

The defendant received $1.6 million through curating the site, which he started in 2012 and claimed offered “real blackmail, rape and forced videos of girls all around the world,” court documents assert.

Users paid for video packs for download via email through cryptocurrency, such as bitcoin and Ether, or with credits earned by uploading new videos, authorities said. The site rejected “fake, amateur . . . or acted movies” that did not portray real sexual violence, U.S. officials said.

As part of the prosecution, the Justice Department also filed a civil forfeiture complaint seizing 303 virtual currency accounts allegedly used by customers around the world.

“This Office will not allow predators to use lawless online spaces as a shield,” Timothy J. Shea, the U.S. attorney for the District of Columbia, said in a statement.