According to the CAMS Study Guide, the most commonly used risk criteria for assessing the money laundering and terrorist financing risks are country risk, customer risk, and product and service risk. These criteria are based on the FATF Recommendations and the Basel Committee's guidance on sound management of risks related to money laundering and financing of terrorism.
Country risk refers to the level of exposure to potential money laundering and terrorist financing activities in a specific jurisdiction, based on factors such as the quality of its AML/CFT regime, its level of corruption, its political and economic stability, its involvement in illicit activities, and its cooperation with international bodies.
Customer risk refers to the level of exposure to potential money laundering and terrorist financing activities associated with a specific customer or customer segment, based on factors such as the nature and purpose of the business relationship, the source and destination of funds, the type and volume of transactions, the customer's profile and behavior, and the customer's geographic location.
Product and service risk refers to the level of exposure to potential money laundering and terrorist financing activities associated with a specific product or service offered by a financial institution, based on factors such as the complexity, transparency, anonymity, and accessibility of the product or service, the delivery channels and payment methods used, and the degree of oversight and monitoring applied.
Reputation risk is not a risk criterion for assessing the money laundering and terrorist financing risks, but rather a potential consequence of failing to manage those risks effectively. Reputation risk refers to the potential damage to the public trust and confidence in a financial institution due to its involvement or association with money laundering and terrorist financing activities, whether directly or indirectly.
References:
* CAMS Study Guide, 6th Edition, Chapter 2: Risk Assessments, pp. 41-461
* FATF Recommendations, Recommendation 1: Assessing Risks and Applying a Risk-Based Approach2
* Basel Committee on Banking Supervision, Sound management of risks related to money laundering and financing of terrorism, June 2017, pp. 9-143

A suspicious transaction report (STR) is a document that financial institutions must file with the relevant authorities when they detect or suspect any activity that may be related to money laundering, terrorist financing, or other criminal offences. An STR should include the details of the customer, the transaction, the reason for suspicion, and any other relevant information.
One of the indicators of suspicious activity is the use of financial instruments, such as checks, money orders, or cashier's checks, that are drawn on other institutions and deposited in amounts under the currency reporting thresholds. This may suggest that the customer is trying to avoid the detection and reporting of large cash transactions, which is a technique known as structuring or smurfing. Structuring is illegal and may indicate that the customer is laundering money from illicit sources or evading taxes.
Another indicator of suspicious activity is the use of financial instruments that are sequentially numbered, meaning that they have consecutive serial numbers. This may suggest that the customer has obtained the instruments from the same source or issuer, and that they are using them to launder money or finance illegal activities. Sequentially numbered instruments may also indicate that the customer is involved in fraud, such as check kiting or counterfeit checks.
Therefore, if a bank conducts a quarterly review on a retail customer's account and finds that the customer has made a number of large deposits of financial instruments drawn on other institutions in amounts under the thresholds, and that the instruments were sequentially numbered, the bank will most likely file an STR. This is because this activity does not fit the customer's historical profile, and it raises a high level of suspicion that the customer is engaged in money laundering or other criminal activities.
References:
CAMS Study Guide - 6th Edition, Chapter 4, Section 4.2, page 108
Answers to Frequently Asked Questions Regarding Suspicious Activity Reporting and Other Anti-Money Laundering Considerations, Question 5, page 7 Anti-money laundering - handling suspicious activity, Section 6.3, page 3 Tell us about suspicious activity that may be linked to money laundering, Section 3, page 1

Reference:
https://www.ifc.org/wps/wcm/connect/e7e10e94-3cd8-4f4c-b6f8-1e14ea9eff80/45464_IFC_AML_Report.pdf?M