According to the ACAMS Study Guide, 6th Edition, page 184, "The decision to close an account should be made in consultation with the institution's legal counsel and AML compliance officer, and in accordance with the institution's policies and procedures." Closing an account may not always be the best option, as it may trigger the customer's suspicion, interfere with law enforcement investigations, or expose the institution to legal risks. Therefore, the institution should carefully weigh the pros and cons of closing an account, and follow its own internal guidelines.
References:
ACAMS Study Guide, 6th Edition, page 184
What steps should the institution take? - Exam4Training
Suspicious Transaction Report (STR) / Suspicious Activity Report (SAR) | AML-CFT

Cryptocurrency is a digital or virtual currency that uses cryptography to secure and verify transactions.
Cryptocurrencies are decentralized and operate outside the control of any central authority, such as a government or a bank. This makes them attractive for money launderers, who can use them to transfer funds anonymously, quickly, and globally, without leaving a trace or being subject to regulation. Cryptocurrencies pose more risk of money laundering than other sources of money, such as wire transfers, credit cards, or money service businesses, which are subject to more oversight, verification, and reporting requirements.
References:
CAMS Study Guide, 6th Edition, Chapter 1, Section 1.9, page 37
CAMS eLearning Course, Module 1, Lesson 9
ACAMS Crypto Hub
Reference: https://complyadvantage.com/knowledgebase/money-laundering-crypto-exchanges/