The purchaser being a nominee is a red flag that indicates high potential for money laundering in a real estate purchase. A nominee is a person or entity that acts on behalf of another person or entity, usually to conceal the identity or beneficial ownership of the real owner. Money launderers may use nominees to purchase real estate with illicit funds, and then transfer the property to the real owner or sell it for a profit. This way, they can obscure the source and ownership of the funds, and integrate them into the legitimate economy12.
ACAMS, CAMS Examination Study Guide, 6th Edition, Chapter 3, pp. 77-78
FATF, Money Laundering and Terrorist Financing through the Real Estate Sector, June 20073, pp. 19-20

This is stated in the Certified Anti-Money Laundering Specialist (the 6th edition) manual on page 595, which states: "Potential indicators of money laundering associated with Trust and Company Service Providers include the use of legal persons in jurisdictions with strict secrecy laws, structuring cash deposits into third party accounts, multi-jurisdictional wire transfers with no legal purpose, and frequent deposits to or withdrawals from bank accounts."

Wire transfers to high-risk jurisdictions and large cash deposits from a high-risk jurisdiction are two red flags that may indicate money laundering. These activities suggest thatthe customer is trying to move funds from or to a country that has weak anti-money laundering (AML) controls, or that is known to be a source or destination of illicit funds12. Wire transfers can also be used to obscure the origin or destination of the funds, or to layer transactions through multiple accounts or intermediaries3. Large cash deposits can indicate that the customer is trying to avoid the reporting or record-keeping requirements that apply to cash transactions, or that the customer is dealing with proceeds from illegal activities45. The other two options are not necessarily red flags, as the bank may have legitimate reasons to allow cash deposits, and the client may reside in a high- risk jurisdiction for legitimate reasons.
1: FFIEC BSA/AML Examination Manual, Appendix F: Money Laundering and Terrorist Financing Red Flags, Geographic Concerns, 6; 2: AML Red Flags - What are the Top 10 Indicators?, ComplyAdvantage, 5; 3: FFIEC BSA/AML Examination Manual, Appendix F: Money Laundering and Terrorist Financing Red Flags, Transaction Has Unusual Features, 6; 4: FFIEC BSA/AML Examination Manual, Appendix F: Money Laundering and Terrorist Financing Red Flags, Unusual Source of Funds, 6; 5:
Money Laundering Red Flags | Key Behaviours and Indicators, High Speed Training, 8.
Reference:https://aml-cft.net/library/banks-amlcft-red-flags/

The Egmont Group is an international body of Financial Intelligence Units (FIUs) from around the world. Its primary purpose is to serve as a forum for FIUs to exchange information, and it also sets international standards for AML/CFT measures. Additionally, the Egmont Group does not serve as a prudential regulator for global financial institutions or as an authoritative body in the field of anti-corruption.

The practice of brokerage firms maintaining securities as nominees and the speed of the transactions are two factors specific to the securities industry that increase the exposure to money laundering risk. Nominee accounts can be used to conceal beneficial ownership and obscure transaction trails. The speed of transactions can make it difficult to detect and prevent suspicious activity in real time.