Members of the Criminal Investigation Division (C.I.D.) are the plain clothes Detectives of the department. They report directly to the Sergeant of Detectives who in turn answers to his/her Division Commander.

C.I.D. is the investigative arm of the department. Detectives are assigned their case load by the Sergeant of Detectives or Youth and Family Services Sergeant  who weekly reviews their cases with them. Detectives are responsible for the investigation of all major crimes (felonies) committed within the department's jurisdiction. This includes developing and following up on all possible leads until an arrest has been made or the case has been declared inactive by the Sergeant.

Detectives are also responsible for the preparation of clear and concise reports and must be prepared to deliver comprehensive and intelligent testimony in court, even under intense cross-examination.

C.I.D. members work closely with agents of the F.B.I., the Drug Enforcement Administration, the Bureau of Alcohol, Tobacco and Firearms, the Secret Service, the Immigration and Naturalization Service, the U.S. Marshall's Office, the U.S. Attorney's Office and other Federal and State law enforcement officials.

Detectives receive specialized training in areas such as arson investigation, homicide/suicide, crime scene search, lab techniques, crime scene photography, etc., either at the Maine Criminal Justice Academy or at other accredited schools throughout the nation.

Included within the Criminal Investigation Division is the Youth and Family Services Unit. This Unit is composed of three Liaison Officers, the Domestic Violence Coordinator, DARE Officers and Child Emergency Response Coordinator, all who report directly to the Youth and Family Services Sergeant.

The Liaison Officers (L.O.'s) are responsible for the investigation of crimes involving juveniles. This includes crimes committed by juveniles and those crimes committed against them such as child neglect, sexual abuse, etc.

They maintain very close ties with local youth throughout the year and maintain offices in some of the city's schools. Many students and parents seek out the officers for guidance and counseling.

The Youth Aid Unit , through the work of the Liaison Officers, offers many programs throughout the year. Programs such as school bus safety, Halloween safety, winter safety, gun safety and bicycle safety are presented to children in the lower grades (K-3) in every school in the city. The older children and teens receive educational programs on drug abuse, personal safety, hunter safety, etc.

Liaison Officers are often called upon to deliver lectures to civic groups and parent/teacher meetings.

Another innovative position within the Criminal Investigation Division is the Child Emergency Response Coordinator. Working closely with the Maine Department of Human Services, the C.E.R.C. Officer investigates possible cases of child neglect and renders assistance to families whose children may be at risk.

The Criminal Investigation Division, through its Commander, the Sergeant of Detectives and Youth and Family Services Sergeant,  is also responsible for the Internal Affairs function of the department.