According to the Anti-Money Laundering Specialist (the 6th edition) study guide, when a financial institution receives a law enforcement inquiry, it should cooperate as much as possible and respond to all formal requests for information, unless there is a valid objection that can and should be made1. The institution should also file a suspicious transaction report (STR) if the inquiry or the customer's activity triggers any red flags or indicators of money laundering or other financial crimes2. Additionally, the institution should monitor the account for suspicious activity and review the money laundering risk posed by the account, as these are part of the ongoing due diligence and risk assessment processes3. Closing the account immediately is not a recommended action, as it may alert the customer or interfere with the investigation4.
References:
1: ACAMS, CAMS Certification Package - 6th Edition, Chapter 4, page 121
2: ACAMS, CAMS Certification Package - 6th Edition, Chapter 4, page 122
3: ACAMS, CAMS Certification Package - 6th Edition, Chapter 4, page 123
4: ACAMS, CAMS Certification Package - 6th Edition, Chapter 4, page 124

The bank's current anti-money laundering program is inadequate because it does not include a process for monitoring customer account activity, which is a key component of detecting and reporting suspicious transactions. The fact that the consultant and the bank have mutual clients does not affect the risk rating of those customers, nor does it justify a lower level of scrutiny. The bank should revise its procedures to ensure that it has a comprehensive and risk-based approach to customer due diligence, transaction monitoring, and reporting.
References:
CAMS Certification Package - 6th Edition, Chapter 3: Compliance Standards for Anti-Money Laundering (AML) and Combating the Financing of Terrorism (CFT), pp. 67-69.
FATF Guidance for a Risk-Based Approach: Legal Professionals, pp. 10-11, 19-20.
BSA/AML Internal Audit: PwC, pp. 1-2.

The anti-money laundering officer (AML officer) is responsible for overseeing the implementation and effectiveness of the anti-money laundering (AML) program of a financial institution. The AML officer should have sufficient authority, independence, and access to resources to perform this role. Reporting to the Sales Director may compromise the independence and objectivity of the AML officer, as the Sales Director may have conflicting interests or incentives that could influence the AML officer's decisions or actions. The AML officer should report to a senior management level that is independent of business functions and has direct access to the board of directors or a relevant committee. This would ensure that the AML officer can communicate any AML issues or concerns to the board without any interference or undue influence from the business functions.
References: = Some of the references that support this answer are:
* ACAMS Study Guide for the CAMS Certification Examination, Chapter 2, Section 2.2.1, page 41:
"The AML officer should report to a senior management level that is independent of the business line and has direct access to the board of directors or a relevant committee."
* Money Laundering Reporting Officer: The Role Of MLRO, Section "Role Of Money Laundering Reporting Officer": "The MLRO should have independent monitoring and should be able to connect directly with people who make business decisions, such as senior management or the board of directors."
* Money Laundering Reporting Officer (MLRO)? | Dow Jones, Section "What is a Money Laundering Reporting Officer (MLRO)?": "A Money Laundering Reporting Officer (MLRO) is tasked with overseeing a firm's compliance with the Financial Conduct Authority's (FCA) rules on money laundering. ... The MLRO should have sufficient authority and independence within the firm to carry out their responsibilities effectively."