Reports are crucial in criminal reports. They provide information about investigation progressions which are used in the court of law as evidence. To write a criminal investigation report, the investigator needs to follow several rules when writing the report to ensure that it makes sense and it can be understood well when presented in a court of law. Like other report writings, criminal reports should focus on the grammar and also good use of vocabularies. Also, the report should have a good flow of events. This paper is going to discuss the key things to be considered when writing criminal investigation reports.