How to Become a Criminal Investigator: Unraveling Mysteries

By Dr. Matthew Loux  |  03/02/2026

Criminal investigators are an integral part of the justice system. Solving crimes and putting offenders behind bars is what brings many people to this career path. Making sure justice is served can be intellectually challenging and provides the opportunity to make a real difference.

What Do Criminal Investigators Do?

Also known as detectives or special agents, criminal investigators are law enforcement professionals who investigate serious crimes, such as:

• Homicides
• Frauds and other financial-related crimes
• Cybercrimes
• Drug trafficking
• Human trafficking
• Sexual crimes, such as sexual assault cases
• Domestic violence

Criminal investigators are also responsible for investigating national security threats, terrorism, and drug smuggling.

Unlike other law enforcement officers, who work on multiple smaller cases and have other routine tasks, investigators work on one case for a long period. They must have the patience for case building and evidence collection.

Alternate Criminal Investigator Job Titles

Depending on the agency and jurisdiction, criminal investigators may be known as: 

• Detectives 
• Criminal investigators 
• Special agents 
• Investigators (local, state, or federal) 

Where Do Criminal Investigators Work?

Criminal investigators can be employed by:

• Local police departments
• County sheriff’s offices
• State law enforcement agencies
• Local law enforcement agencies
• Federal agencies such as the Federal Bureau of Investigation (FBI) or Drug Enforcement Administration (DEA)
• Military or defense investigative services, such as the Office of Special Investigations (OSI) or Naval Criminal Investigative Service (NCIS)
• Regulatory or financial crime units
• Corporations such as banks and insurance companies

Each setting has different entry requirements, responsibilities, and career progression paths. However, career opportunities vary depending on an organization’s requirements and a job candidate’s skills. The types of roles listed are examples and are not guaranteed.

Why Choose a Career as a Criminal Investigator?

Before committing to this career path, it’s important to understand why people choose this profession. Key motivations to become a criminal investigator may include: 

• Public service – Protecting communities during emergency response calls and seeking justice for victims
• Intellectual challenge – Solving complex cases using logic, evidence, and analysis 
• Variety – Staying intellectually stimulated because no two cases are the same
• Advancement opportunities – Applying for specialized or supervisory roles once sufficient experience and knowledge are gained

Criminal Investigators’ Job Duties

The job duties of criminal investigators typically include conducting surveillance and analyzing evidence and crime scenes. The regular day of a criminal investigator may involve:

• Reviewing past case files and evidence
• Interviewing witnesses and suspects
• Working with forensic science professionals
• Coordinating with a prosecutor about cases
• Collaborating with other law enforcement professionals
• Writing affidavits and testifying in court

Criminal investigators often work closely with forensic science experts to solve cases, ensuring that evidence is properly collected and analyzed. They may also participate in special task forces or fugitive operations teams, depending on the nature of their assignments.

Some criminal investigators handle a range of crimes. Other choose a specialization, such as organized crime or narcotics.

Eight Steps for Becoming a Criminal Investigator

Becoming a criminal investigator can be a rigorous but fulfilling process. To ensure candidates are ready for the job, they must demonstrate their aptitude, experience, and personal mettle.

There are also various steps to go through, such as:

1. Meeting the eligibility requirements
2. Earning a degree
3. Developing essential skills
4. Developing writing skills
5. Becoming a police officer
6. Gaining law enforcement experience
7. Completing employment tests and background checks
8. Completing specialized investigator training

Step 1: Meeting Eligibility Requirements 

The baseline qualifications for most criminal investigator positions include:

• Being at least 21 years of age
• U.S. citizenship (for most agencies)
• A valid driver’s license
• No criminal history
• A high school diploma or a General Educational Development (GED) certificate
• Physical fitness and psychological fitness (requirements vary depending on the agency or organization)

Federal government agencies may have additional requirements. For instance, there may be a mobility agreement (a willingness to move to a new location) and more stringent background checks.

Step 2: Earning a Degree

For some police roles, there may be no formal education needed, especially for entry-level positions. However, most law enforcement services prefer or require candidates to have at least a college degree to remain competitive in hiring.

A bachelor’s degree is often necessary for federal positions. Typically, aspiring criminal investigators pursue a bachelor’s degree in a field such as:

• Criminal justice
• Criminology
• Forensic science
• Psychology
• Sociology
• Cybersecurity or computer science
• Banking or finance (for solving crimes involving money)

Depending on the role, taking courses in a foreign language may also be beneficial. For instance, the ability to communicate in a second language can be useful for interviewing non-English speakers.

Some people who become criminal investigators decide to pursue more advanced education, such as:

• A master’s degree in criminal justice, forensic psychology, or accounting
• A law degree (for specific investigative roles or for support prosecuting investigative roles)

Having advanced education may enhance a candidate’s credibility and demonstrate a commitment to the profession. Some United States government roles such as FBI special agents require an advanced degree as part of their eligibility requirements.

Step 3: Developing Essential Skills

Anyone aspiring to become a successful criminal investigator must have some basic skills, such as:

• Analytical thinking – for weighing physical evidence, seeing connections, and examining records to uncover important clues
• Communication skills – necessary for conducting interviews with witnesses and suspects
• Attention to detail – the ability to recognize that collecting evidence results in small pieces of information that can be crucial in deciding a case
• Ethical judgment – sustain the law and maintain constitutional rights
• Emotional intelligence – being able to engage victims, suspects, and coworkers in a respectful and professional manner

Candidates may gain these types of skills through military service, police department work, private security internships, or similar life experiences. They may also seek out a seasoned criminal investigator as a mentor.

Step 4: Developing Writing Skills 

The ability to write is one of the most fundamental and least appreciated, skills an investigator can possess. Documentation can have a significant impact on the outcome of a case.

The sheer volume of documentation criminal investigators create is overwhelming. Documents include:

• Incident and follow-up reports
• Search warrant affidavits
• Arrest warrants
• Probable cause statements
• Case summaries

When investigators present clear, compelling documentation, that can strengthen a case and earn the respect of prosecutors and presiding judges. Aspiring criminal investigators may take report writing courses to strengthen these skills.

Step 5: Becoming a Police Officer 

In most cases, it is necessary to be a police officer before you can move on to being a criminal investigator. Training at the police academy provides the basic skills for investigations as well as preparation in:

• Emergency and crisis management
• Ethics and civil rights
• Criminal law procedures
• Report writing
• Firearm safety and handling
• Defensive tactics
• Physical fitness

Police academy programs commonly take future officers through real-world scenarios to determine if they’re up to the job. Most police and detectives must graduate from their agency’s training academy before completing on-the-job training.

After graduating from a police academy, officers have to go through field training under the guidance of a veteran officer. This stage is meant to develop the officer’s competencies and decision making.

Step 6: Gaining Law Enforcement Experience 

After serving for a number of years, a police officer is eligible to become a criminal investigator. Most departments require two to five years of experience as a patrol officer before applying for promotion to detective or investigator.

Prospective detectives should focus on building a strong foundation during their time as patrol officers to prepare for advancement. Commonly, eligible applicants need:

• Strong arrests and case building
• Professional behavior
• Initiative and problem-solving abilities
• Positive feedback from superiors
• Research and report writing aptitude

Step 7: Completing Employment Tests and Background Checks

Employers tend to be very selective when hiring detectives or criminal investigators. Apart from meeting specific educational and professional requirements, candidates may also need to:

• Successfully complete oral boards and interviews
• Take written tests such as internal promotion exams
• Pass various background investigations, including drug tests

For federal agencies, applicants do not have to have prior patrol experience. However, they must complete in-house training for the specific agency and demonstrate core skills through the Federal Law Enforcement Training Center (FLETC).

Step 8: Completing Specialized Investigator Training

Once selected for a job, criminal investigators may receive additional training in areas such as:

• Crime scene processing
• Interview and interrogation methods
• Evidence handling
• Forensic analysis
• Search warrants preparation
• Digital/cyber investigations
• Surveillance
• Criminal law

Training may continue throughout an investigator’s career. Promotional exams and advanced training in areas like crime scene management or interviewing techniques are necessary for many specialized roles.

Challenges for Criminal Investigators

The work environment for a criminal investigator can be demanding and intense, often requiring long shifts, including on-call hours during nights, weekends, and holidays. This career path also comes with:

• Exposure to violence and traumatic situations at crime scenes
• High stress and responsibility, especially with violent crimes
• Intense scrutiny and ethical expectations
• Physical demands
• Emotional challenges of working with victims

Compassion fatigue is a natural outcome of this type of work, as a crime scene investigator is exposed to the underside of human behavior. Due to the rigors of the job, many agencies have started to prioritize mental health support, such as counseling as well as proactive stress management interventions. These crucial resources aid with resiliency.

Ethics and Professional Responsibility

A criminal investigator have a lot of enforcement authority, so ethical behavior is a must. Key principles include:

• Respecting constitutional rights
• Maintaining integrity with evidence
• Being transparent, honest, and responsible
• Avoiding conflicts of interest

Collaboration in the Criminal Justice System

Criminal investigators’ responsibilities do not occur in a vacuum. A large part of the job intersects with other professionals, such as prosecutors.

In a preparatory phase of a criminal inquiry, a crime scene investigator works with prosecuting attorneys to:

• Validate that the gathered evidence is legally admissible
• Spot legal implications that could derail a case
• Teach prospective witnesses the essentials of providing testimony
• Identify defense attorneys’ tactics and making necessary preparations for court

A strong professional relationship between investigators and prosecutors can greatly enhance the efficiency of an investigation.

Criminal Investigators’ Roles in the Courtroom

Investigators have to provide court testimony. As expert witnesses, they have a role that requires poise and professionalism. To aid in felony convictions, they must be able to articulate their thoughts clearly and succinctly.

Testifying in court is a rite of passage that investigators develop with mentorship from others who have testified.

How Technology Has Reshaped Investigations 

Technology has become ubiquitous in investigations today. Criminal investigations must understand how to accurately capture and maintain digital evidence, such as:

• Mobile phone data 
• Social media activity 
• Global positioning satellite (GPS) and location data 
• Surveillance videos 
• Emails and messages 

Digital evidence must be captured, analyzed, and presented in accordance with the law and with respect to privacy. For example, the National Institute of Justice developed a digital evidence manual to support federal government agencies in developing digital evidence policies.

Forensic Technology 

The technology available for forensic science and forensic criminology has also progressed exponentially. Criminal investigators now rely on:

• DNA analysis
• Fingerprint databases 
• Ballistics 
• Facial recognition 

The U.S. Government Accountability Office has addressed the need for policies to increase the transparency of how these tools are used.

Direct Entry Investigator Programs

Some state and federal organizations have direct entry investigator positions available for applicants with specific education or skills. The typical backgrounds of these candidates include:

• Cybersecurity professional with skills in digital forensics
• Financial crime specialist (helpful for prosecuting members of criminal organizations)
• Certified public accountant
• Veterans with military intelligence or investigative services
• Investigative lawyers and other legal professionals

Candidates entering through these pathways are typically given considerable training to compensate for the absence of traditional law enforcement experience.

Transitioning from the Military

Military service provides a strong base for a career in criminal investigation. Many agencies have hiring preferences for candidates with military experience.

Veterans are usually very disciplined, have leadership capabilities, and knowledge of organized investigative procedures. Applicable career paths include:

• Military police
• Criminal investigation divisions
• Military intelligence
• Security forces

Teaching and Consulting Opportunities 

Some investigators move into:

• Instructional design or law enforcement education
• Criminal justice pedagogy
• Consulting
• Expert witness testimony

These avenues provide investigators the chance to continue to build their knowledge while reducing time in the field.

Tips for Success

Becoming a criminal investigator is a process, one that takes a considerable amount of time. Achieving this role entails being adequately prepared, exhibiting a high level of ethical behavior and emotional strength, and maintaining a willingness to learn.

Thriving in this area of criminal justice requires:

• Maintaining physical and mental fitness
• Continuing professional education
• Honing writing skills
• Building a professional network with their agency
• Staying up to date with laws and new investigative technologies

For those individuals who are driven by justice, analytical thought, and social service, criminal investigation may be a gratifying field of work. By anticipating the demands of the profession, prospective investigators can pursue fulfilling, impactful career opportunities.

The Bachelor of Arts in Criminal Justice at AMU

For adult learners interested in studying different areas of criminal justice, American Military University (AMU) offers an online Bachelor of Arts in Criminal Justice. Students who enroll in this bachelor’s degree program can take courses in criminology, U.S. law enforcement, criminal investigation, and ethics in criminal justice. Other topics include the criminal legal process and constitutional law.

This B.A. in criminal justice has four concentrations, so that students can choose the concentration that best suits their professional interests:

• Organizational law enforcement leadership
• General
• Entrepreneurship
• Maritime law enforcement

For more details about the B.A. in criminal justice, visit AMU’s criminal justice degree program page.

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