The Major Crimes Unit consists of several divisions which are Homicide, Vice, Narcotics, ABC, Gangs, Evidence, Domestic Violence and Child Abuse/Child Sex Crimes.

The Homicide division investigates homicides, suicides and other deaths that are not attended by a doctor or hospice. The Homicide division works closely with the Tennessee Bureau of Investigation and other agencies in an attempt to identify and apprehend suspects involved in a homicide. In the event of a homicide, they utilize the drug unit to assist in the investigation. When investigating suicides and other deaths (natural or accidental causes), the Homicide division treats them as homicides until the evidence shows otherwise. In the event of a homicide or serious violent crime, the drug agents will assist the Homicide division with their investigation.

The narcotics division of the Major Crimes Unit deals with a wide variety of criminal activity. They investigate drug crimes from the small-scale user to the large-scale distributor. The division accomplishes this by utilizing detailed intelligence gathering and undercover operations. They work closely with other jurisdictions and agencies in their attempts to discourage drug activity within the city.

The unit regulates the issuance of beer permits and periodically performs compliance checks on those establishments that sell alcohol within the city. The ABC agent works closely with other city departments such as Building and Codes and the Fire Department to insure that patrons of these establishments are provided with a safe environment for their entertainment.

In February 2003, the unit acquired a K-9 named "Tuffy". The K-9 specializes in narcotics detection and is utilized primarily in an interdiction capacity, available to all divisions with the Police Department. In addition to this, the K-9 also participates in many public relation events to include displays in the local school system.

The unit also regulates adult entertainment within the city as well as investigating vice related crimes such as gambling and prostitution.

The Domestic Violence Division is responsible for verifying all written reports involving domestic violence or abuse within the city of Clarksville. The Domestic Violence Detective also designated to follow up on domestic related cases where the primary aggressor could not be determined. After investigating the matter, if an arrest is warranted, the arrest will be made by the Domestic Violence Division. The Domestic Violence Division also holds training classes for officers within the Police Department, as well as outside agencies who request assistance in training on domestic related incidences.

The Child Advocacy Center consists of the Director, Forensic Interviewer, and Detectives with the Clarksville Police Department. They also work hand-in-hand with the state Child Protective Services. Together they work cases involving serious physical abuse, sexual abuse, and internet sex crimes involving children.

Evidence or property that is collected by officers of the Clarksville Police Department is turned into the Evidence Room for safekeeping and to protect the integrity of the evidence, until it is adjudicated by the courts. Property is disposed of in accordance with the law, and policies of the department. Evidence is transported to the Tennessee Bureau of Investigations crime lab if tests are necessary. Our evidence room has over 50,000 pieces of property and evidence in storage. The evidence room also is responsible for transporting items to the annual police auction.