The Cook County Sheriff's Office is a local law enforcement agency that serves Cook County, Illinois. It is the second largest Sheriff's department in the United States with over 6,900 members. It is headed by the Sheriff of Cook County, currently Thomas Dart. Due to its size, the Cook County Sheriff's Office divides its operations by task into 8 departments, the most recognizable of which is the Cook County Sheriff's Court Services Department. The much smaller Cook County Sheriff's Police Department provides traditional police services in unincorporated Cook County while the Department of Corrections staffs the Cook County Department of Corrections.
All Cook County Sheriff's Police Officers are Cook County Sheriff's deputies, but not all Cook County Sheriff's deputies are Sheriff's Police Officers. Police Officer is a job function and title within the Cook County Sheriff's Police Department. It should be noted that all Cook County Sheriff's Deputies have police powers regardless of their particular job function or title. Like other sheriffs' departments in Illinois, the Sheriff's Police can provide all traditional law-enforcement functions, including county-wide patrol and investigations irrespective of municipal boundaries, even in the city of Chicago, but has traditionally limited its police patrol functions to unincorporated areas of the county because unincorporated areas are the primary jurisdiction of a Sheriff's Department in Illinois.
The Sheriff's Police patrol services are often not required in incorporated cities because the cities such as Chicago have established their own police departments. The 500-600 member Sheriff's Police Department would not have the personnel necessary to supply full police services to all incorporated areas in Cook County especially in a municipality such as Chicago. Sheriff's deputies, outside the Sheriff's Police, provide the other services of the sheriff, such as guarding the various courthouses in Cook County, running and guarding the 9,800-detainee Cook County Jail, and overseeing other offender rehabilitation programs.
Sheriff's Office Departments
The Cook County Sheriff's Office is divided into eight departments. 
- The Cook County Sheriff's Boot Camp is designed to provide non-violent offenders a strict detention program based on military discipline, fundamental vocational skills, education and alcohol/substance abuse treatment. In addition, the Boot Camp features an 8-month long post-detention supervision program where participants must return to the Boot Camp on a daily basis to continue educational programming.
- The Department of Corrections is one of the largest single-site pre-trial holding facilities in the country. Sheriff's Correctional Officers are responsible for the security of more than 9,000 detainees, most of whom are awaiting trial in the criminal court system.
- The Court Services Department provides security for all courtrooms and aides judges and other court officials in the orderly operation of daily business. In addition to providing courtroom security, deputy sheriff’s operate metal detectors at the entrance of each of the courthouse facilities where many arrests are made every year of individuals attempting to bring weapons and contraband into the facilities.
- The Department of Community Supervision and Intervention draws its population from the DOC and from the court system. Each of DCSI’s Divisions is unique in its operations, but together they form a cooperative and mutually supportive team that offers a sliding scale of corrections alternatives from community service to incarceration.
- The Sheriff's Police Department is charged with patrolling unincorporated areas of Cook County. Approximately 109,000 people live in unincorporated communities. Sheriff's Police also assist suburban police departments in routine police operations as well as drug, vice and gang crimes operations. Contact Sheriff's Police
- The Department of Women's Justice Services is a newly created department withint the Cook County Sheriff's Office which administers gender responsive drug treatment programs for female offenders.
- The Jail Diversion and Crime Prevention Division was designed to make the Cook County Sheriff’s Office more useful and accessible to residents.
- The Office Of Professional Review investigates allegations of various types of misconduct throughout the Sheriff's Office.
|Officer||Date of Death||Details|
|Deputy Sheriff Frank E. Nye||Gunfire|
|Policeman Sam F. Kaiser||Motorcycle accident|
|Policeman Frederick C. Bryant||Motorcycle accident|
|Policeman Meyer Joseph (Jack) Lapine||Motorcycle accident|
|Policeman Robert (Ruby) Schanbaum||Vehicular assault|
|Policeman Frank J. Christian||Vehicular assault|
|Deputy Sheriff Joseph Law Sr.||Gunfire|
|Investigator John A. Rusnak||Automobile accident|
|Investigator Michael W. Ridges||Gunfire|
|Correctional Officer Jeffery Blakey||Assault|
|Deputy Sheriff Alfred Brown Jr.||Assault|
|Patrol Officer James F. Knapp||Automobile accident|
50 W. Washington
Phone: (312) 603-6444