The Criminal Investigations Bureau is supervised by the Special Services Commander. It consists of three detectives assigned to the unit, and typically handles most criminal & sensitive crimes investigations. They also maintain the Department intelligence files, property inventory, and investigative equipment.

Most cases are generally initiated as a patrol officer responds to the scene of a crime. If the need for specialized assistance is apparent, or the investigation exceeds the scope of the field officer's duties, a detective may be assigned. Criminal cases referred to the Bureau are under the direct supervision of Detective Sergeant Dahlen.

Each detective is veteran officer, selected for the job because of their unique and proven abilities. They are given extensive training to deal with a wide variety of criminal activity, and employ the most modern tools for the collection of evidence. Two members of staff also have specialized certification in Computerized Voice Stress Analysis (CVSA), and are commonly called upon by other police agencies for assistance.

The Bureau also has formal agreements in place with their counterparts in other agencies for a Major Case Investigation Squad. Should a member unit become taxed beyond it's abilities, the Squad can be quickly assembled to mitigate the incident.

Additionally, the Department assigns one patrol officer to a drug task force operated by the Stateline Area Narcotics Team (SLANT). The organization consists of officers from Southern Wisconsin and Northern Illinois agencies. SLANT officers have jurisdiction throughout all of Illinois and portions of southern Wisconsin.