By Dr. Jarrod Sadulski  |  10/03/2023

how to become a criminal investigator


Becoming a criminal investigator is a common goal for law enforcement officers. Criminal investigators are a crucial part of the criminal justice system and may work in a federal, state, county, or local law enforcement agency.

The foundation of being a good criminal investigator is to typically first gain experience on patrol as a police officer. Often, a patrol officer will need to serve a certain amount of time on road patrol, according to agency policy, after graduating police academy training.

During this time, aspiring investigators gain valuable experience conducting field investigations by applying the skills they learned in the police academy. These skills will be an asset when they progress from police officers to criminal investigators.

For an officer, being a part of a criminal investigation while on road patrol provides valuable insight into how a crime scene investigation is conducted. That knowledge can help officers when they pursue criminal investigator positions.

Law enforcement experience is essential in being a good criminal investigator. Aspiring criminal investigators should take every opportunity to assist detectives on crime scenes while they serve as road patrol officers.

Investigators should also gain a firm understanding of criminal law and a deep understanding for how criminal investigators work. The purpose of criminal investigations is to discover the truth and solve crimes.

Often, criminal investigators will interview witnesses and suspects, and they will visit crime scenes. With the assistance of a crime scene unit, criminal investigators analyze and collect evidence within the crime scene, document findings, and ensure that vital evidence is properly preserved. Investigators will often retrace the steps of the victim and will seek out motives and modus operandi associated with the crime.


Steps to Become a Criminal Investigator

The requirements for becoming a criminal investigator vary by state and agency. Learning how to become a criminal investigator often occurs through reviewing agency policy, seeking mentors from other agency law enforcement officers who can provide insight into the field, and gaining field experience.

Forensic science plays an important role in criminal investigations and is an area that police officers who wish to become a criminal investigator may wish to learn. Most law enforcement agencies and police departments have police detectives who serve as criminal investigators.

Criminal investigators in a federal law enforcement agency are more likely to have a specialization in a particular area. For example, criminal investigators in the Drug Enforcement Administration (DEA) typically focus on counter drug trafficking while criminal investigators in the Internal Revenue Service (IRS) typically focus on crime related to taxes.


Key Skills for Criminal Investigators

In addition to gathering evidence and writing reports, interviewing witnesses and suspects is a crucial role that criminal investigators fill. Consequently, developing strong communication skills is useful.

Investigators will often develop the communication skills that enable them to display empathy and gain the trust of a witness or suspect. For example, a criminal investigator may tell a suspect that the crime he or she is being investigated for is not as serious as other crimes. As a result, the suspect may become more comfortable speaking with the investigator under the belief that the crime is not as serious as it could be.

Detectives and criminal investigators write detailed case reports. Detectives and criminal investigators apply critical thinking to put the pieces of a crime’s puzzle together through collecting evidence, reviewing written records, applying criminal theory, and utilizing investigative experience.

To gather evidence, a criminal investigator may return to a crime scene multiple times as the investigation unfolds. Law enforcement detectives bring justice to crime victims and solve crimes. Criminal investigators are typically detectives in a police department or special agents in federal agencies such as the Federal Bureau of Investigation (FBI).

An additional skill for criminal investigators includes being detail-oriented. This skill is essential because criminal investigators prepare criminal case packages to be presented to the courts for criminal prosecution.

Ideally, case packages must be fully complete and error-free. A criminal investigator should have strong writing and analytical skills to clearly articulate any findings clearly.

Often, investigators testify in court, so they need to be articulate and have good public speaking skills. Being able to detect deception while interviewing witnesses and suspects through monitoring voice inflection, body mannerisms, emotions, and eye contact is a highly useful for skill for a criminal investigator.

A firm understanding of criminal law is also useful for criminal investigators as they often deal with complex issues involving searches and seizures under the Fourth Amendment and the right against self-incrimination under the Fifth Amendment.

Solving crimes as an investigator takes a large amount of patience, an ability to see the big picture, and the ability to work well with others. Investigators may be placed in dangerous situations, such as when they conduct surveillance. To combat this danger, physical fitness and weapons training is critical for anyone who wants to be a criminal investigator.


Private Investigators

Similar to law enforcement criminal investigators, private investigators conduct investigations. Unlike law enforcement criminal investigators, private investigators do not have the ability to conduct arrests. Also, they are more limited in scope in what they are permitted to do in an investigation.

For example, a criminal investigator who is a law enforcement officer may conduct search warrants where someone has a reasonable expectation of privacy and make arrests. However, private investigators do not have that ability.

Private investigators commonly offer services such as locating missing persons, verifying background information, and searching public records. Retired or former law enforcement officers commonly serve as private investigators. Private investigators may also be part of a criminal defense investigation by collecting information related to a criminal case.

Some law enforcement agencies may have education requirements to be a criminal investigator. Some agencies may require an associate or bachelor's degree, while some may just require a bachelor's degree.

There are often different criminal investigation positions within an agency. For example, some agencies separate the investigators by assigning some to property crimes and personal crimes. Larger agencies may have dedicated homicide detective positions.

Aspiring criminal investigators may wish to examine the different criminal investigator opportunities that exist within a specific law enforcement agency because the career opportunities may differ. Criminal investigations provide a unique opportunity to help others through solving crime and bringing justice to victims.


Criminal Justice Degrees at American Public University

American Public University offers several bachelor’s and master’s degrees to suit the knowledge needs of students who want to learn how to become a criminal investigator. These online criminal justice degrees enable students to develop a wide knowledgebase while also providing flexibility for adult learners with busy schedules:

Note: This program is not designed to meet the educational requirements for professional licensure or certification in any state. This program has not been approved by any state professional licensing body and does not lead to any state-issued professional license.


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About the Author
Dr. Jarrod Sadulski

Dr. Sadulski is an Associate Professor within our School of Security and Global Studies. He has over two decades in the field of criminal justice. His expertise includes training on countering human trafficking, maritime security, effective stress management in policing and narcotics trafficking trends in Latin America. Jarrod frequently conducts in-country research and consultant work in Central and South America on human trafficking and current trends in narcotics trafficking. He also has a background in business development. Jarrod can be reached through his website at for more information.

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