The Investigation Division of the Hillsdale County Sheriff's Office is comprised of specialized deputies who investigate crimes against property, persons and children. They also work closely with and file cases with the District Attorney's office relating to felony crimes committed in Hillsdale County.
- Detective Bureau - Investigates crimes against property and persons in Hillsdale County and works closely with District Attorney's office in felony cases.
- Crime Scene Bureau - Aiding in the investigation of crimes ranging from fingerprinting to working homicide scenes.
- Death Investigation Unit - Assists County Medical Examiner in determining cause of death and works in conjunction with the Detective and Crime Scene Bureaus.
- Internet Crime Unit - Responsible to find and arrest criminals who use the Internet to harm others.