How to hire a criminal investigator: skills, tests and interview questions

A criminal investigator is a professional who looks into suspected crimes, collects and protects evidence, interviews witnesses and suspects, and writes up findings that can stand up in court or in front of a regulator. Police forces, state and federal agencies, banks, insurers, hospitals and large employers all hire criminal investigators, and a weak hire can cost a case.

TL;DR:

• Decide between a sworn, corporate or private criminal investigator, because each needs a different hiring process.
• Look for investigative technique, evidence handling, legal knowledge, interviewing, records analysis, report writing, attention to detail and integrity.
• Sworn roles need academy training. Corporate roles often prefer a Certified Fraud Examiner (CFE). Private investigators usually need a state license.
• The BLS median for detectives and criminal investigators was $93,790 a year in May 2025, about $45 an hour.
• Follow seven steps: define the role, write the job description, source candidates, run a skills test, set a case-file work sample, hold a structured interview, then check background and make the offer.
• Interview questions with strong answer examples, and a job description template you can copy.

What does a criminal investigator do?

A criminal investigator gathers facts about a suspected crime and turns them into evidence that a prosecutor, court, regulator or employer can act on. The work runs from the first report of an incident to the final written case file, and in many roles to testimony in court.

Typical duties include:

• Opening cases and planning the line of inquiry.
• Collecting, documenting and preserving physical and digital evidence with a clear chain of custody.
• Interviewing victims, witnesses and suspects, and spotting gaps between their accounts.
• Reviewing records such as bank statements, phone data, access logs and CCTV.
• Running surveillance and background checks on people of interest.
• Working with forensic specialists, prosecutors, lawyers and other agencies.
• Writing reports that a reader with no context can follow.
• Testifying in court or at hearings.

The Indeed employer page for this role adds coordinating search and arrest warrants and directing crime scene staff, which apply only to sworn investigators. That difference is the first decision you need to make.

Which type of criminal investigator are you hiring?

Criminal investigator roles fall into three groups, and each one needs a different hiring process. Sworn investigators work for police and government agencies and hold arrest powers. Corporate investigators work inside banks, insurers, hospitals and other companies on fraud and misconduct. Private investigators work for law firms or agencies and usually need a state license.

Most private-sector teams that search for a criminal investigator are hiring the second type. Fraud is the reason. The ACFE 2026 Report to the Nations, as reported by Accounting Today, estimates that organizations lose about 5% of revenue to fraud each year, with a median loss of $104,000 across 2,402 cases in 143 countries. A typical scheme ran 12 months before anyone caught it, and 43% were found through tips, which means someone has to investigate those tips well.

What skills should a criminal investigator have?

A good criminal investigator combines technical skills, such as evidence handling, legal knowledge and records analysis, with judgment skills, such as interviewing, attention to detail and integrity. The table below lists the skills that separate strong candidates and how to check each one before you hire.

The Bureau of Labor Statistics lists communication, empathy, good judgment, perceptiveness and leadership as core qualities for police and detectives. For corporate roles, add comfort with spreadsheets and case management systems, since most of the evidence is digital.

Pro tip: Weight report writing heavily. An investigator who finds the truth but cannot write it down clearly loses the case at the prosecution or disciplinary stage.

Which qualifications and certifications should you ask for?

Criminal investigator qualifications depend on the type of role. Sworn roles have fixed legal requirements, while corporate and private roles give you more room to hire on skills.

• Education: The BLS says entry-level education for police and detectives ranges from a high school diploma to a college degree, and many federal agencies expect a bachelor's degree. A degree in criminal justice, criminology, accounting or forensic science is common but rarely required for corporate roles.
• Academy and POST training: Sworn investigators complete a training academy and on-the-job training, and are usually at least 21 years old, according to the BLS.
• Certified Fraud Examiner (CFE): The most useful credential for corporate and financial crime roles. The ACFE eligibility rules require ACFE membership, 40 qualifying points to sit the exam, 50 points to be certified and at least two years of fraud-related experience. A bachelor's degree usually earns 40 points.
• Private investigator license: Most states license private investigators, so check the rules in each state where the person will work.
• Experience: Ask for a clear case record, not just years. Some public employers set a hard minimum: one Rhode Island attorney general posting on Indeed asked for 3 years of sworn law enforcement experience.

For digital-heavy roles, look for evidence of training in digital forensics tools, and test it rather than trusting the resume line.

How much does a criminal investigator earn?

Detectives and criminal investigators in the US earned a median of $93,790 a year in May 2025, according to the BLS. The BLS counts 120,500 people in this occupation. That works out to about $45 an hour on a 2,080-hour year.

Pay varies widely by employer type, region and specialism. Federal agencies and financial crime units usually pay above the median, while entry-level private investigator roles can pay far less. Benchmark against local postings before you set the range, and publish it: candidates skip postings with no pay range, and several US states require one.

How do you hire a criminal investigator, step by step?

Hiring a criminal investigator works best as a seven-step process in which skills evidence is gathered before the interview, not after. The steps below suit corporate teams and can be adapted for public agencies, which add fitness tests and a polygraph.

1. Define the role: Decide between sworn, corporate and private investigator work, list the case types (fraud, theft, misconduct, cybercrime) and pick the three or four skills that matter most.
2. Write the job description: State the case mix, reporting line, travel, on-call needs, pay range and any license or certification you require. Use the template later in this guide.
3. Source candidates: Post on general and specialist boards and reach out to the networks listed below.
4. Screen with a skills test: Send every applicant the same short online test so you compare everyone on the same evidence before reading resumes in depth.
5. Run a case-file work sample: Give shortlisted candidates a mock case file and ask for a short written report. The report shows how they will work on a real case.
6. Hold a structured interview: Ask every candidate the same questions, score each answer against a rubric, and include a witness role-play.
7. Check background and make the offer: Run reference, conflict-of-interest and background checks, then make the offer.

For background checks run through a third-party company, the FTC and EEOC guidance for employers says you must give a stand-alone written notice, get written permission, and send pre-adverse and adverse action notices before rejecting someone based on the report. Our guide to background checks covers the wider process.

How do you test a criminal investigator's skills?

Criminal investigator skills are best tested in two layers: a short online test that screens every applicant on core knowledge, then a case-file work sample for the shortlist. Interviews alone reward confident talkers, which is a real risk in a job built on questioning people.

A practical test stack looks like this:

• Role knowledge: The Testlify criminal investigator test covers investigative techniques, evidence collection and analysis, interview and interrogation, report writing, and legal and ethical considerations in 15 questions and about 15 minutes.
• Reasoning: A critical thinking test shows how a candidate weighs evidence and avoids jumping to conclusions.
• Detail: An attention to detail test catches people who miss mismatched dates, names and amounts.
• Ethics: A business ethics and compliance test suits corporate and financial crime roles.
• Digital evidence: For cyber or digital-heavy roles, add a computer forensics test.

For the work sample, build a case file of 8 to 12 pages: an incident report, two witness statements that disagree on one key fact, a short transaction log or access log, and a policy extract. Give the candidate 60 to 90 minutes to list the leads, flag the contradiction, name the evidence they would secure first and write a one-page report. Score it on accuracy, order, legal awareness and clarity.

Key takeaway: Test before you interview. The online test removes guesswork from the shortlist, and the case file shows how the person thinks when no one is prompting them.

Where can you find criminal investigator candidates?

Criminal investigator candidates come mostly from law enforcement, military police and investigations units, audit and compliance teams, and licensed PI firms. The best channels are:

• Law enforcement transitions: Officers and detectives moving to the private sector bring interviewing and evidence skills.
• Military investigators: Veterans from military police and criminal investigation units.
• Professional bodies: The Association of Certified Fraud Examiners and the International Association of Crime Analysts have job boards and local chapters.
• Audit, compliance and AML teams: Strong records analysts who can grow into investigation roles.
• Job boards and LinkedIn: General boards plus targeted search for titles such as fraud investigator, special investigator and detective.
• Universities: Criminal justice, criminology and forensic accounting programs for junior roles.
• Referrals: Your current investigators know who did good work on joint cases.

What interview questions should you ask a criminal investigator?

Criminal investigator interview questions should test how a candidate plans a case, handles evidence, questions people and stays within the law. Ask every candidate the same questions and score answers on a 1 to 5 scale.

Investigation and evidence

1. Walk me through a case you led from the first report to the outcome. What would you do differently? Strong answer: a clear sequence, named decisions and an honest lesson.
2. How do you keep the chain of custody for digital evidence such as a laptop or phone? Strong answer: isolating the device, imaging, logging every handover.
3. Two witnesses give opposite accounts of the same event. What do you do next? Strong answer: look for independent evidence before choosing a side.
4. Tell me about a time a lead you trusted turned out to be wrong. Strong answer: noticed early, changed course, recorded why.

Law and ethics

1. What makes evidence inadmissible, and how do you avoid it? Strong answer: specific examples such as missing consent, broken custody or unlawful search.
2. Describe a time you found a conflict of interest during a case. Strong answer: declared it and stepped back or escalated.
3. How do you protect confidential case data, including on your phone? Strong answer: concrete habits, not general promises.

Interviewing and communication

1. How do you prepare for an interview with a suspect who has a lawyer present? Strong answer: planned topics, known facts, calm tone.
2. How do you approach a frightened or traumatized witness? Strong answer: rapport first, open questions, no leading.
3. Tell me about a time you testified or presented findings to a panel. Strong answer: stuck to facts, handled challenge without getting defensive.

Judgment and pressure

1. How do you decide which cases to close when your caseload doubles? Strong answer: a clear rule based on risk and evidence.
2. Tell me about a high-pressure case and how you managed your workload and stress. Strong answer: specific methods and support they used.

For more question sets, see the Testlify criminal law scenario interview template.

Criminal investigator job description template

Criminal investigator job descriptions work best when they name the case mix and the skills you will test. Copy and adapt this template.

Job title: Criminal Investigator (or Fraud Investigator, Special Investigator)

About us: [Company] is a [industry] company with [size and locations]. Our investigations team looks into fraud, theft and misconduct that affect our customers, staff and partners.

What you will do

• Lead investigations into suspected fraud, theft, misconduct and other criminal activity.
• Collect, document and preserve physical and digital evidence with a clear chain of custody.
• Interview complainants, witnesses and subjects, and record their statements.
• Analyze records such as transactions, access logs, emails and phone data.
• Work with legal, compliance, HR, law enforcement and regulators.
• Write clear case reports and recommendations, and give evidence at hearings or in court when needed.

What you bring

• [X] years of investigation experience in law enforcement, the military, audit, compliance or a PI firm.
• Working knowledge of criminal law, evidence rules and [relevant regulations].
• Strong interviewing and report writing skills.
• Comfort with spreadsheets and case management tools.
• Certified Fraud Examiner (CFE) or state PI license preferred, if relevant.
• Ability to pass a background check.

Pay and benefits: [Pay range], [benefits], [on-call or travel details].

How we hire: A short online skills test, a case-file exercise, a structured interview and a background check.

For a related role, see the fraud investigator job description template.

What mistakes lead to a criminal investigator mis-hire?

Criminal investigator mis-hires usually come from trusting the badge or the years on the resume instead of checking the work. The most common mistakes are:

• Hiring on rank or tenure: Years of service do not prove someone can run a fraud case or write a clear report.
• Skipping the writing sample: Report quality decides outcomes, so test it every time.
• Ignoring the type of role: A great patrol detective may not know how to trace funds through a bank's systems, and a forensic accountant may freeze in a hostile interview.
• Loose conflict checks: Ask about outside work, family links to suppliers and prior employers before the offer.
• Unstructured interviews: Different questions for each candidate make fair comparison impossible and weaken your position if a decision is challenged.

How does Testlify help you hire criminal investigators?

Testlify is a skills assessment and AI interviewing platform that helps hiring teams screen criminal investigator candidates on evidence before the interview.

• Ready-made role test: The criminal investigator test sits in a library of 3,500+ tests, so you can add critical thinking, attention to detail, ethics and computer forensics tests in one assessment.
• Your own case questions: 25+ question types, including file upload, open-ended and video answers, let you add a case-file task and a written report to the same assessment. The AI test builder can turn your job description into a draft assessment.
• Structured interviews: One-way video interviews and AI interviews ask every candidate the same questions and score answers against your criteria.
• Fair and secure: 20+ proctoring checks, including webcam snapshots, copy and paste blocking and AI assistance detection. See anti-cheating and proctoring.
• Fits your stack: Two-way sync with 100+ ATS and HRIS tools, including Workday, SAP SuccessFactors and Greenhouse. See integrations.

Pricing is credit-based: you pay only when a candidate starts an assessment, and there is a 7-day free trial with no credit card.

Frequently asked questions

Ready to hire your next criminal investigator on skills?

Start with the criminal investigator test and add your own case-file task, or book a demo to see how Testlify fits your investigations hiring.