Recently, the old case of the AAX exchange has been re-discussed, and I can't help but want to sort out the underlying logic behind it.

Going back to 2022, AAX was one of the largest cryptocurrency exchanges in Hong Kong, with over 2 million users. But in November, it suddenly collapsed, first stopping withdrawals citing counterparty risk, then disappearing altogether. Subsequent investigations revealed deeper issues—founder Su Weiyi was accused of holding the private keys to user funds, with 25,100 ETH transferred out, and funds spread across different blockchains via cross-chain bridges. By 2024, he was arrested in Hong Kong.

The reason this case is worth attention is not just because AAX itself went bankrupt, but because it exposed a bigger problem: why is cryptocurrency so easily used as a tool for money laundering?

Honestly, the decentralization and anonymity of crypto are a double-edged sword. On one hand, they offer freedom; on the other, they become a breeding ground for criminals. Think about it—traditional finance has banks and regulatory bodies overseeing everything, but crypto transactions only require a wallet address, with no need to link to real identities. Plus, tools like Tornado Cash mix coins, breaking down and reassembling funds once they go in, making it impossible to trace the source. Cross-chain bridges are even more ruthless, directly transferring assets to blockchains with looser regulations, layered with privacy protocols to hide the trail. Finally, funds can be easily exchanged into fiat currency, enabling money laundering.

I notice many people still think of the AAX incident as just a "platform run-off," but the legal issues involved are actually more complex. Crimes like aiding and abetting, concealing criminal proceeds, and money laundering may seem similar, but their legal elements differ greatly in crypto transactions. The key depends on which stage the behavior occurs, the awareness of upstream crimes, and whether the funds are considered criminal proceeds.

From a prevention perspective, exchanges need to do more than just claim compliance. First, they must enforce strict KYC, prohibit anonymous accounts, and conduct enhanced due diligence for large or cross-border transactions. Second, they should establish real-time monitoring systems, integrating on-chain data, user information, and third-party risk databases, deploying anomaly detection models. Lastly, they need an independent compliance department, regularly train staff, and actively cooperate with regulators.

The lesson from AAX is clear: crypto money laundering methods are diverse, from coin mixing to layered transfers and OTC off-market trades, each step can be exploited. This not only disrupts financial order but also fuels crimes like scams and corruption. Whether for ordinary users or service providers, raising risk awareness and fulfilling KYC and AML obligations are essential, along with monitoring suspicious transactions. Only through the joint efforts of users, platforms, and regulators can transaction security truly be maintained.