These groups accounted for a fifth of the global illicit cryptocurrency market, which experts estimated at over $82 billion. Analysts estimate that these networks laundered the equivalent of $44 million per day on average.

The criminals' primary operating platform is the Telegram messenger. So-called "guarantee" platforms operate there—channels that act as intermediaries between sellers of illegal services and clients. Chats openly advertise "laundromat" services, and photographs of mountains of cash are published as proof of liquidity.

For transactions, criminals prefer to use stablecoins such as USDT and USDC, which are pegged to the dollar, rather than Bitcoin or Ethereum.

"If you're engaged in illegal activity, the last thing you want is to lose money. "You're already paying for the laundering process... you don't want a bad week for Bitcoin to wipe out another 10% of your funds," explained Andrew Firman, head of national security intelligence at Chainalysis.

These networks' clients include not only fraudsters but also sanctioned government entities, including hackers from North Korea.

Although the networks speak Chinese, their operational centers are often located outside of China, in Cambodia and Myanmar. This is due to Beijing's hardline stance: cryptocurrency trading is banned in China, and organizing criminal syndicates carries the death penalty. China recently executed 11 members of a fraudulent gang based in Myanmar.

In addition to money laundering, these organizations are involved in human trafficking and supplying equipment to fraudulent call centers in Southeast Asia.

Experts warn that combating these groups is complicated by their resources and cross-border nature.