How to Become a Criminal Investigator in Illinois

The most recent crime statistics released by the state of Illinois indicate that while the overall crime rate has dropped by about 2.8 percent between 2010 and 2011, the proportion of crimes classified as violent remains extremely high at around 14%.

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To ensure the safety of its citizens, it is imperative that qualified, motivated detectives, or criminal investigators, serve the state of Illinois and continue to help decrease the crime rate, especially the violent crime rate. By becoming a detective at the state-level in Illinois, applicants will be joining the ranks of the Illinois State Police Division of Operations criminal investigations section where they ill work in partnership with local and federal agencies to break up international drug cartels, solve murders, and disrupt terrorist plots.

Becoming a Detective with the Illinois State Police Division of Operations

Detectives working at the state level serve within the Illinois State Police Division of Operations, which also oversees the Illinois State Highway Patrol. These detectives are known as special agents.

Becoming a special agent begins by qualifying as a state trooper and serving for two years before being promoted to detective.

Education and Experience Requirements:

The State of Illinois has made it a point to emphasize secondary education for state trooper applicants.

There are four options for satisfying education and experience requirements to become a member of the Illinois State Police. All applicants must meet ONE of the following requirements:

  • Hold a bachelor’s degree in any major (criminology, forensics, crime scene investigations, criminal justice, and psychology are among the most relevant)


  • Hold an associate’s (AA or AS) degree and have either three years of full time experience as a police officer for the same department, or three years of active military experience


  • Hold an associate’s degree (AS) in either Law Enforcement or Criminal Justice along with three years of full time experience as a police officer for the same department, or three years of active military experience
  • No post-secondary education, but has been honorably discharged after actively serving in the military and has been awarded at least one qualifying medal OR is an active member of the Illinois National Guard or one of the reserve components of the United States Armed Forces and has received one qualifying medal (Qualifying medals: Global War on Terrorism Expeditionary Medal, Korean Defense Service Medal, Afghanistan Campaign Medal, Southwest Asia Service Medal, Iraq Campaign Medal, Kosovo Campaign Medal)

All education requirements must be met with at least a C average or better:

General Requirements:

In addition to the educational requirements, all applicants must also:

  • Be at least 21 years of age

    • An applicant may apply at 20 years old if the Option 4 educational requirement is met
  • Be a citizen of the United States with no felony convictions
  • Have a valid driver’s license
  • Be willing to accept assignment anywhere in Illinois
  • Pass a written exam
  • Successfully pass a physical fitness exam
  • Undergo medical and psychological examinations
  • Attend police academy training

There is an online application process for becoming a special agent, although applicants must be aware that the state does not take applications until they have set a date for a Merit Board Trooper Test. However, applicants may fill out a notification request so they will be notified when a date for the test is set.

Investigative Units within the Illinois State Police Division of Operations

The Illinois State Police Division of Operations criminal investigations section is made up of specialty divisions concerned with specific types of crime. Special agents in these divisions worth throughout the twenty-one different districts and seven investigative zones that comprise the state:

  • Homicide division
  • Sexual Assault division
  • Vehicular Theft division
  • Fraud Division
  • Forgery Division

It may be beneficial for aspiring candidates to tailor their secondary education to a specific division if they know where their interests lie.

Candidates will spend two years as a state trooper before being able to request a transfer to a different division.

Detectives within Illinois City and County Law Enforcement Agencies

Besides finding employment with the state Operations Division, interested applicants may also be interested in more localized jobs with county or city investigation’s divisions. There are many varieties of local jobs, ranging from work in a huge city, like Chicago, or a less pressurized situation like a job with a county correctional division further south in the state. In either case, there is an opportunity to help serve, protect, and better a community. A few of the different job opportunities in the state of Illinois are:

  • The Bureau of Detectives with the Chicago Police Department
  • Detective Division of the Peoria County Sheriff’s Office
  • General Investigations Unit with the Cook County Sheriff’s Office
  • Investigative Division of the Kankakee County Sheriff’s Office
  • The Investigative Services Bureau with the Rockford Police Department
  • Investigations Division of the Champaign Police Department
  • The Criminal Investigations Unit with the Normal Police Department
  • The LaSalle Police Department Detective Division
  • The Knox County Sheriff’s Department Investigations Division
  • The Detective Division with the DuPage County Sheriff’s office

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