Which of the following describes the addresses used by 9/11 hijackers?

• A. Permanent addresses
• B. Mail boxes and were changed frequently
• C. Same address and telephone numbers
• D. Box addresses that never changed

Answer: (B)

The key idea here is how illicit actors manage their contact points to avoid being traced. Using mailbox-style addresses and changing them frequently is a tactic to keep investigators guessing and to break ties between a person, their location, and their communications. In this context, relying on mail drops or P.O. boxes that aren’t tied to a fixed residence makes it harder to establish a stable, verifiable identity or location.

Permanent addresses or keeping the same address and phone numbers would create a clear, trackable trail. Addresses that never change would likewise be easy to associate with a single individual. By contrast, frequent changes of mailbox addresses align with attempts to obscure origin and movement, which is why that option best describes the addresses used. This pattern is a red flag in AML contexts because it signals efforts to evade surveillance and accountability.