According to the ACAMS Study Guide 6th Edition, Chapter 2, page 38, one of the steps that a financial institution should take when it suspects money laundering activity is to file a suspicious transaction report (STR) or a suspicious activity report (SAR) to the relevant authorities. This will alert the regulators and law enforcement of the potential money laundering scheme and provide them with valuable information to trace the funds and identify the perpetrators.
Another step that a financial institution should take is to identify any unusual or suspicious wire transfers initiated by casas de cambio to jurisdictions outside of Mexico that bear no apparent business relationship with that casa de cambio. This could indicate that the casas de cambio are involved in layering and integration stages of money laundering, where they are moving the illicit funds across borders and disguising their origin and ownership. The financial institution should monitor and document these wire transfers and report them to the authorities if necessary.
Option B is not a relevant step to trace funds through the bank, as it does not provide any information about the source, destination, or purpose of the funds. A decrease in the sale of large denomination U.S. bank notes to casas de cambio by the bank could be due to various factors, such as market demand, exchange rates, or regulatory changes, and does not necessarily indicate money laundering activity.
Option C is also not a relevant step to trace funds through the bank, as it does not indicate any connection to the suspected money laundering scheme. Deposits by casas de cambio that include third-party items, such as sequentially numbered monetary instruments, could be legitimate transactions that are part of the normal business operations of the casas de cambio. Unless there is evidence that these deposits are related to the sale of large denomination U.S. bank notes or the Mexican syndicate, they are not useful for tracing the funds.
References:
* ACAMS Study Guide 6th Edition, Chapter 2, page 38
* Combating Money Laundering and Other Forms of Illicit Finance
* Sting Operation Snares Casa de Cambio for Allegedly Laundering Millions Through U.S. Banks