Detecting money laundering is indeed a complex challenge, particularly in its later stages, for several reasons:

• Layering: Money launderers often engage in layering, which involves complex transactions to obscure the illicit origin of funds. This can include transferring money through multiple accounts, shell companies, and even across international borders, making it difficult to trace the original source.
• Integration: Once the money is successfully layered, it is integrated into the legitimate financial system through investments in real estate, businesses, or other assets. At this stage, the funds appear to be derived from legitimate sources, making detection very challenging.
• Sophistication of Methods: Money launderers are constantly developing new and more sophisticated methods to evade detection, such as using cryptocurrencies, online gambling platforms, and trade-based money laundering techniques.
• Legal and Regulatory Frameworks: While there are legal and regulatory frameworks in place to combat money laundering, such as the Bank Secrecy Act and anti-money laundering (AML) regulations, these frameworks may not always be effective in detecting sophisticated laundering schemes.

However, it is important to note that financial institutions and law enforcement agencies are also continuously improving their detection methods, using sophisticated technologies such as artificial intelligence and machine learning to identify suspicious transactions and patterns. International cooperation and information sharing also play a crucial role in detecting and preventing money laundering.

For more detailed information, you might find the following resources helpful:

• Financial Action Task Force (FATF): https://www.fatf-gafi.org/
• U.S. Department of Justice - Money Laundering: https://www.justice.gov/criminal-resource-manual/title-9-offenses/money-laundering