Detectives assigned to the Criminal Investigation Division (CID) are responsible for conducting in-depth, comprehensive investigations into crimes reported to the Department. Additionally, detectives conduct other investigations including background investigations of all candidates applying to join the Frederick Police Department. CID also serves as liaison with allied federal agencies including the:
- Bureau of Alcohol
- Diplomatic Security Service
- Federal Bureau of Investigation
- Immigration and Customs Enforcement
- Tobacco and Firearms
- United States Marshal's Service
- United States Secret Service