In Criminal Case, every time a murder occurs, a murder case must be filed in the police report with the police department that the murder is associated with.
Each case is usually started with a short cut scene, usually with Samuel King, the chief of the Grimsborough Police Department telling David Jones, your teammate and the inspector with the Grimsborough Police Department, or Frank Knight and Amy Young, the your teammates and inspectors with the Pacific Bay Police Department, and yourself of the murder. Then, you and your partner (or partners) must go to the crime scenes and solve the murders to find out which one of your suspects was the murder of the case you are trying to solve. You will search multiple crime scenes per case, find clues, interrogate suspects, and analyze certain clues (as well as give the victim's body an autopsy) to help you find the killer and put him (or her) behind bars.
Currently, there are 87 cases in Criminal Case. There are 56 cases throughout Grimsborough and then the rest of them are in Pacific Bay.