High School

Because detectives work on a wide variety of cases, if you are interested in this field, you are encouraged to take a diverse course load. English, American history, business law, government, psychology, sociology, chemistry, and physics are suggested, as are courses in journalism, computers (especially computer security), and a foreign language. The ability to type is often needed. To become a police detective, you must first have experience as a police officer. Hiring requirements for police officers vary, but most departments require at least a high school diploma.

Postsecondary Training

In some police departments a college degree may be necessary for some or all positions. Many colleges and universities offer courses or programs in police science, criminal justice, or law enforcement. Newly hired police officers are generally sent to a police academy for job training.

After gaining substantial experience in the department—usually about three to five years—and demonstrating the skills required for detective work, a police officer may be promoted to detective. In some police departments, candidates must first take a qualifying exam. For new detectives there is usually a training program, which may last from a few weeks to several months.

Private detective agencies usually do not hire individuals without previous experience. A large number of private investigators are former police officers. Those with no law enforcement experience who want to become private investigators can enroll in special private investigation schools, although these do not guarantee qualification for employment. A college degree is an admissions requirement at some private investigation schools. These schools teach skills essential to detective work, such as how to take and develop fingerprints, pick locks, test for the presence of human blood, investigate robberies, identify weapons, and take photographs. The length of these programs and their admissions requirements vary considerably. Some are correspondence programs, while others offer classroom instruction and an internship at a detective agency. Experience can also be gained by taking classes in law enforcement, police science, or criminal justice at a college or university.

Certification or Licensing

The National Association of Legal Investigators awards the certified legal investigator designation to private detectives and investigators who specialize in cases that deal with negligence or criminal defense investigations. ASIS International offers the professional certified investigator credential. Contact these organizations for more information. 

Private detectives and investigators must be licensed in all states except for Alaska, Idaho, Mississippi, South Dakota, and Wyoming—alhough some cities in these states have their own licensing criteria. In general, states that have licensing require applicants to pass a written examination and file a bond. Depending on the state, applicants may also need to have a minimum amount of experience, either as a police officer or as an apprentice under a licensed private investigator. An additional license is sometimes required for carrying a gun.

The civil service board usually gives both a written and physical examination. The written test is intended to measure a candidate's mental aptitude for police work, while the physical examination focuses on strength, dexterity, and agility.

Other Requirements

In almost all large cities the hiring of police officers must follow local civil service regulations. In such cases candidates generally must be at least 21 years old, U.S. citizens, and within the locally prescribed height and weight limits. Other requirements include 20/20 corrected vision and good hearing. Background checks are often done.

Experience while working as police officers or during postsecondary education or training programs is how most move into the career of detective. Those interested in this career should be inquisitive, have good observation skills, a keen memory, and well-developed oral and written communication skills. Being fluent in a second language is also helpful. The large amount of physical activity involved requires that detectives be in good shape. An excellent moral character is especially important.