Money Laundering Investigations: Putting the Puzzle Pieces Together

Money laundering investigations rarely begin with a complete picture.

Most of the time, investigators start with scattered pieces: an alert, a transaction pattern, customer information, product usage, dollar amounts, negative news, referrals, subpoenas, or information-sharing requests. The real skill is not simply collecting data. The real skill is knowing which pieces matter, how they connect, and what picture they form.

This article is a professional summary and reflection based on the ACAMS Today article “Money laundering investigations: Putting the puzzle pieces together” by Anne Marie Lacourse, published on June 17, 2026.

The article explains AML investigations through a practical comparison: a jigsaw puzzle. In a normal puzzle, we already know the final image. In AML investigations, we usually do not. That is why investigators must work carefully, logically, and with professional skepticism.

Alerts Are Only Starting Points

An alert does not automatically mean suspicious activity. It only tells us that something may require review. The investigator must analyze the facts, understand the customer, evaluate possible explanations, and decide whether the activity is truly suspicious or reasonably explainable.

This is where hypothesis testing becomes important. A good investigator should ask: What behavior triggered the alert? What lawful explanations may exist? What evidence supports or weakens each explanation? Is the remaining uncertainty reasonable based on the customer, product, and risk profile?

This approach helps avoid rushed decisions. It also makes the investigation easier for quality assurance teams, auditors, regulators, and examiners to understand.

Customer Understanding Is the Frame of the Puzzle

In any AML investigation, customer knowledge is critical. The investigator needs to understand the customer profile, expected activity, business type or occupation, source of funds, beneficial ownership, geographic exposure, products used, past alerts, prior reviews, and any negative news or OSINT findings.

For a new customer, deeper review may be necessary because the institution has limited historical knowledge. For an existing customer, prior activity and previous reviews may help. But familiarity should never replace professional skepticism. A known customer can still be involved in suspicious activity, and a long relationship does not automatically mean low risk.

Product Risk Matters

Different products create different financial crime risks. Cash, wires, official checks, ACH transfers, payment platforms, trade finance, and other value-transfer mechanisms can all be misused in different ways.

Some products are attractive to criminals because they allow fast movement of funds, limited transparency, indirect ownership, or rapid conversion of value. That is why investigators should not review transactions in isolation. They must understand how the product works, why the customer is using it, and whether the activity makes sense within the customer’s profile.

Dollar Amounts Can Tell a Story

Dollar amounts are often important clues. Repeated cash deposits just below reporting thresholds may indicate structuring. Small deposits through multiple individuals may suggest mule activity. Even-dollar transactions by a business may raise questions if the business normally should have taxes, fees, or variable invoice amounts.

But the same facts may be interpreted differently by different investigators. One investigator may see suspicious structuring. Another may see a business trying to reduce cash kept on the premises for security reasons. This is why documentation, evidence, and balanced judgment matter.

Avoiding Confirmation Bias

AML investigations often operate in a gray area. Not every unusual transaction is suspicious. Not every explanation is sufficient. Not every concern should automatically lead to a SAR filing decision.

Investigators must be careful not to start with a conclusion and then search only for facts that support it. Minimum review standards, clear procedures, strong documentation, and quality assurance review can help reduce confirmation bias.

A good investigation should not only answer what decision was made. It should explain why the decision was reasonable.

Documentation Is a Control

One of the most important compliance lessons is this: if it was not documented, it did not happen.

Documentation should not be treated as an administrative task after the real work is done. It is a core control within the AML program. Strong documentation protects the institution during audits, regulatory examinations, law enforcement inquiries, and litigation. It also shows that SAR filing or non-filing decisions were based on facts, risk, and professional judgment.

My Key Takeaway

Money laundering investigations are not about mechanically clearing alerts or filing SARs. They are about building a defensible picture.

Investigators must connect customer information, transaction behavior, product risk, dollar amounts, ownership structure, external intelligence, and reasonable explanations. The goal is not just to reach a decision. The goal is to show the path taken to reach that decision.

That is what makes an AML investigation strong, defensible, and professionally sound.

Md Ahsan Habib, CAMS, CDCS | Vanguard Professional Academy