FREE ABMDI Study Guide 2026: The Complete Registry Exam Walkthrough

This free ABMDI study guide walks through the highest-yield content the ABMDI Registry (basic) certification exam tests, organized by the eight official content domains and the National Institute of Justice scene-investigation framework the exam is built on.^[1][3]

It is interactive, not a wall of text: every domain has worked scenarios, comparison tables, labeled diagrams, and built-in flashcards — taught to the entry-level medicolegal death investigator standard the exam actually measures. The subject is sensitive; the tone throughout is clinical and professional.

Read it domain by domain, then round out your prep with our practice questions and flashcards. The exam has 240 multiple-choice questions across the eight domains.^[1]

ABMDI Registry Exam Snapshot

Investigating Deaths is the single largest domain — the scene work, postmortem changes, and the cause-vs-manner determination are the heart of the job and the exam. Identifying and Preserving Evidence is the next-largest. Because these two carry the most weight, study them first — but every domain appears, so do not skip the smaller ones.^[3]

The percentages above are our approximate study-weighting estimate to help you prioritize — not figures ABMDI publishes as official exam blueprints. ABMDI builds its items to the NIJ National Guidelines for Death Investigation, so the surest preparation is mastering that scene-investigation framework.^[3][4]

How the ABMDI Registry Exam Is Built

The ABMDI Registry (basic) exam is 240 multiple-choice questions built on the National Institute of Justice National Guidelines for Death Investigation — the 1997 guidelines republished in 1999 (and updated in 2024) as “Death Investigation: A Guide for the Scene Investigator.”^[3][4] ABMDI writes its questions, and its experience checklist, to these nationally recognized standards. The eight content domains describe everything a medicolegal death investigator must do — from interacting with agencies and families through the scene work, evidence, ethics, and the science.

ABMDI uses a criterion-referenced passing standard rather than grading on a curve, so you are measured against a fixed competency bar; cited figures cluster around 70–75% correct, but verify the current standard on the official site.^[1] There is no penalty for guessing, so answer every question.

This guide teaches the eight domains as eight study modules, one-to-one with the official content areas, with subsections so you can check off your progress in smaller steps.^[1]

Jurisdiction & Working with Agencies

The first domain — Interacting with Federal, State and Local Agencies — is about who has authority over a death and who controls the scene.^[3] Get the jurisdictional framework right and the rest of the investigation follows.

Medical Examiner vs Coroner

Two systems investigate deaths. A medical examiner is typically an appointed official who is a licensed physician, usually a forensic pathologist, and can perform or oversee the autopsy.

A coroner is most often an elected public official whose qualifications vary by jurisdiction — in some states a justice of the peace or sheriff performs coroner duties. The core distinction is physician-appointed versus elected-lay; both derive authority from state statute and both determine cause and manner of death.^[3]

Reportable Deaths & Scene Authority

Whether a death falls under the office’s jurisdiction is set by state statutes and local ordinances, not by family wishes or a physician’s preference. A reportable death is classically one that is sudden, violent, suspicious, or unattended by a physician, plus any death resulting from injury or trauma — reportable regardless of where or how long after the injury the person dies.

An expected natural death a treating physician can certify (a hospice patient dying of a documented illness) generally falls outside ME/coroner jurisdiction. At the scene, law enforcement controls the overall perimeter, while the ME/coronerholds authority over the body itself — it should not be moved or released without that office’s authorization.

Communicating & Notification

The Communicating domain covers accurate reporting and, critically, identifying and notifying the legal next of kin.^[3] Errors here have real consequences for grieving families.

Next of Kin & the Kinship Order

Next of kin is the closest living blood or legal relative recognized by law to act on the decedent’s behalf. The standard statutory order usually ranks the surviving legal spouse first, then adult children, then parents, then siblings — set by law and statutory priority, not by who reported the death or who arrives first.

A finalized divorce ordinarily removes a former spouse from spousal standing, while a legally recognized domestic partner can hold a spousal-equivalent position ahead of siblings. Relatives in the same tier generally share equal standing, so when they disagree, the investigator documents the dispute and follows office policy or legal guidance. Because tracing kin from a misidentified decedent would notify the wrong family, confirming identity is a prerequisite to identifying next of kin.

Death Notification & Reports

When identity is uncertain, locate kin diligently — start with personal effects, mail, neighbors, and database checks before concluding there are no relatives. Verify competing spousal claims through marriage and divorce records, and when the only relative is legally incompetent, the court-appointed guardianacts in the next-of-kin role. Death notification should be timely, accurate, and delivered with sensitivity; the investigator’s written reports must be clear, factual, and free of unverified conclusions, since they become part of the legal record.

Interacting with Families

The Interacting with Families domain is about gathering the decedent profile — the social and medical history — from relatives, compassionately and accurately.^[3] Families are often the best source of the history that explains a death.

Social & Medical History

The social history captures lifestyle and circumstances the family can describe — recent alcohol, tobacco, and drug use, living arrangements, and occupation. The medical history captures chronic conditions, recent symptoms, the decedent’s medications and their prescribers, and the providers they saw (a recently seen cardiologist is a lead toward records, not a conclusion about the cause).

Recording medications points investigators toward relevant conditions and guides toxicology and records review. Asking when the decedent was last in their usual state of health establishes a baseline and timeframe for any decline.

Sensitivity & Documenting Reported History

Use open, neutral questions(“Can you tell me about any ongoing illnesses the decedent was being treated for?”) — leading or dismissive questions distort the account. Treat family statements as reported history that may be corroborated by medical records, not as findings or as a determination of cause.

Even a vague complaint (“feeling weak for a few days”) is worth documenting, because reported symptoms point toward records and pathology that may explain the death. When a family cannot recall medication names, ask about the pharmacy, the conditions treated, or whether bottles or a list exist — these leads recover the information.

Investigating Deaths: Scene & Postmortem Changes

Investigating Deaths is the largest domain — the scene investigation, the postmortem changes, and the cause-versus-manner determination are the core of the job.^[3] Master this module above all others.

The Scene Investigation (NIJ Phases)

The NIJ guide organizes scene work into six phases: initial notification, arriving at the scene, documenting and evaluating the scene, documenting and evaluating the body, establishing the decedent profile, and completing the investigation (see the diagram above).^[3]

The governing principle is document before you disturb: photograph, note, and sketch the scene and the body in placebefore anything is moved, because the body’s position and its postmortem changes are themselves evidence. Premature movement (for example, an officer relocating the body for responders) can destroy positional evidence such as the lividity pattern.

Postmortem Changes & the Time Since Death

Three early postmortem changes help estimate the postmortem interval (the time since death). Livor mortis (lividity) is the gravity-driven settling of blood into the dependent areas — a reddish-purple stain, pale at pressure points — that becomes “fixed” after several hours (it stops blanching when pressed). A livor pattern that contradicts the body’s position (fixed on the front of a face-up body) indicates the body was moved after lividity set.

Rigor mortis is muscle stiffening that begins in the small muscles (jaw, face), is typically complete around 12 hours, then passes off over the next day; once “broken” by force it generally will not re-form. Algor mortis is the body’s cooling toward ambient temperature, affected by environment, clothing, and body size. No single change dates death precisely — read them together, alongside decomposition and scene clues.

Cause, Mechanism & Manner of Death

Keep three terms distinct. The cause of death is the specific disease or injury that started the lethal chain (a gunshot wound; a heart attack). The mechanism of death is the physiological derangement the cause produced (exsanguination; an arrhythmia).

The manner of death is the medicolegal category of circumstances — Natural, Accident, Suicide, Homicide, or Undetermined (NASH plus Undetermined). The same cause can carry different manners: a drug overdose may be accident, suicide, homicide, or undetermined depending on circumstances the investigator helps establish.

Manner is an opinion based on the totality of the investigation, which is why the investigator’s scene findings often drive it more than the autopsy alone — and why undetermined is the honest classification when the evidence is genuinely ambiguous.

Identifying & Preserving Evidence

The Identifying and Preserving Evidence domain is the second-largest, and it centers on one discipline: chain of custody.^[3] Evidence that cannot be accounted for cannot be trusted in court.

Chain of Custody

Chain of custody is the chronological documentation of everyone who handled, transferred, and stored an item of evidence, from collection through analysis and storage. An unbroken chain establishes that the item presented in court is the same one collected and was not altered or substituted; any unexplained gap — a five-hour stretch with no record of where a specimen was — can be exploited to challenge or exclude the evidence. Each transfer must record the date, time, and identities of the person releasing and the person receiving the item; an informal, unrecorded handoff creates a gap.

Labeling, Sealing & the Body as Evidence

Mark each item with a unique identifier, the collector’s initials, and the date and location of collection. Seal containers with tamper-evident tape and initials across the seal so any later opening is visible. At a complex scene, having a single designated person control evidence collection and transfers prevents confusion and gaps.

Critically, the decedent’s body itself is treated as evidence subject to chain-of-custody documentation — its movement from scene to morgue and through examination is tracked just like a physical item, and it is not released to family until the ME/coroner authorizes it.

Ethical & Legal Responsibilities

The Maintaining Ethical and Legal Responsibilities domain is about objectivity— protecting the investigation from the investigator’s own biases — and the legal duties that surround the work.^[3]

Objectivity & Cognitive Bias

Anchoring bias is relying too heavily on the first information received and failing to adjust as new evidence emerges — for example, accepting a dispatcher’s “obviously a suicide” before arriving. The objective course is to treat early characterizations as unconfirmed leads to be tested against the actual findings.

Other safeguards:

• write down your preliminary impression and deliberately argue against it to surface overlooked evidence;
• evaluate each case on its own evidence rather than assuming it mirrors a prior or high-profile one;
• guard against socioeconomic assumptions changing how rigorously you work;
• treat a gut feeling as a hypothesis to test, not a conclusion;
• and seek peer review on complex or controversial determinations.

When the evidence is genuinely ambiguous, the objective manner is undetermined.

Confidentiality, Scope & Testimony

The investigator works within a defined scope of practice and a chain of authority — law enforcement controls the scene, the ME/coroner controls the body and the cause-and-manner determination. Case information is confidential and released only through proper channels. Documentation must be factual and defensible, because reports and the investigator’s testimony may be examined in court, where any gap, assumption, or unsupported conclusion can be challenged.

Demonstrating Scientific Knowledge

The Demonstrating Scientific Knowledge domain tests the science behind the findings — enough forensic pathology, toxicology, and physiology to interpret a scene and a body correctly.^[3]

Carbon Monoxide, Asphyxia & Toxicology Basics

Carbon monoxide is a classic high-yield topic. It is an odorless, colorless, tasteless gas produced by the incomplete combustion of carbon-containing fuel, so it accumulates without warning in enclosed spaces (a running generator, a faulty furnace). It binds hemoglobin to form carboxyhemoglobin, which gives the skin and lividity a distinctive bright cherry-red color and causes hypoxia — the oxygen-starved brain produces early headache, dizziness, and confusion.

But color alone is not proof: cold refrigerated storage can keep blood pink and mimic it, so blood must be preserved for quantitative carboxyhemoglobin testing. Multiple simultaneous deaths of healthy occupants in one enclosed space strongly suggest a shared toxic exposure.

Decomposition & the Autopsy

Decomposition is the progressive breakdown of the body after death, beginning with greenish discoloration of the abdomen; its degree is one more input to estimating the time since death. The autopsy provides the objective, evidence-based examination behind a cause-of-death determination, and it has two sequential components: the external examination(the body’s surface — identifying features, postmortem changes, injuries) followed by the internal examination (the organs and body cavities).

The scene investigator’s documentation of position, livor, rigor, and injuries directly informs and complements the pathologist’s findings.

Coping with Job-Related Stress

The smallest domain, Coping with Job-Related Stress, recognizes that exposure to traumatic death has a real cost — and that managing it is a professional skill, not a personal weakness.^[1]

Vicarious Trauma, Burnout & Support

Vicarious trauma is a lasting change in an investigator’s beliefs, worldview, and sense of safety from empathetically engaging with others’ trauma. It differs from burnout, which builds gradually from chronic workplace demands and exhaustion, and from compassion fatigue, the emotional cost tied specifically to caring for and being exposed to suffering.

Advanced strain shows as depersonalization and cynicism — treating decedents as objects, families with detachment. Responses to the same scene differ by prior trauma, current stressors, support, and coping resources.

Protective practices include peer support programs (trained colleagues offering early support), critical incident stress debriefings (structured, short-term, confidential group sessions for early intervention — not a substitute for clinical treatment), and recognizing compassion satisfaction, the rewarding side of helping families find answers.

How to Use This Study Guide

Work through the guide one domain at a time. After each one, check it off in the contents to raise your exam-readiness score, then drill the same content in our free practice questions and flashcards — active recall and realistic practice are what move knowledge into exam-day performance.

• Lead with Investigating Deaths and Evidence. The scene work, postmortem changes, cause-vs-manner, and chain of custody are the largest, highest-yield content — start there.
• Anchor everything to the NIJ phases. Most vignettes describe a moment in the investigation; place the question in its scene phase and the correct procedure usually follows.
• Memorize the discriminators. Cause vs mechanism vs manner; the five manners (NASH + Undetermined); livor vs rigor vs algor; ME vs coroner — these recur constantly.
• Document before you disturb. The body and scene are recorded in place before anything is moved; an out-of-place postmortem change is itself evidence.
• Stay objective. Treat early characterizations as leads to test, choose “undetermined” honestly, and protect the chain of custody.
• Then prove it. When a domain feels solid, confirm with our practice questions — build a comfortable margin before exam day.

Common death-investigation concepts ABMDI candidates study and get asked — each answered briefly and backed by an official source (ABMDI, the NIJ scene-investigator guide, NAME, or CDC). Tap any card to test yourself.

ABMDI Glossary

Key ABMDI and death-investigation terms in one place. Hover any dotted term throughout the guide for its definition; the full list is below.

ABMDI

The American Board of Medicolegal Death Investigators — the body that certifies death investigators. Its Registry (basic) certification is the entry-level credential; Board certification is the advanced level.

medicolegal death investigator

An MDI — the official who responds to a death scene on behalf of the medical examiner or coroner to document the scene and body, gather history, and help determine the cause and manner of death.

medical examiner

An appointed official who is a licensed physician, usually a forensic pathologist, and who can perform or oversee autopsies and certify cause and manner of death.

coroner

Most often an elected public official whose qualifications vary by jurisdiction; in some states a justice of the peace or sheriff performs coroner duties. A coroner may be a lay (non-physician) official.

jurisdiction

The legal authority of a medical examiner or coroner office over a death, created and bounded by state statutes and local ordinances that define which deaths are reportable and investigable.

reportable death

A death that statute requires be reported to the ME or coroner — classically a sudden, violent, suspicious, or unattended death, or any death resulting from injury or trauma.

next of kin

The closest living blood or legal relative recognized by law to act on the decedent's behalf; the statutory kinship order usually ranks the surviving legal spouse first.

cause of death

The specific disease or injury that started the lethal chain of events — for example a gunshot wound, a heart attack, or blunt-force trauma.

mechanism of death

The physiological derangement produced by the cause that actually ends life — for example exsanguination (bleeding out), an arrhythmia, or asphyxia.

manner of death

The medicolegal category of the circumstances of death: Natural, Accident, Suicide, Homicide, or Undetermined (NASH plus Undetermined). It is an opinion based on the totality of the investigation.

livor mortis

Lividity — the gravity-driven settling of blood into the dependent (lowest) areas after death, producing reddish-purple staining with pallor at pressure points; it becomes 'fixed' after several hours.

rigor mortis

The stiffening of the body's muscles after death from biochemical changes; it begins in the small muscles (jaw, face), is typically complete around 12 hours, then gradually passes off.

algor mortis

The cooling of the body toward ambient temperature after death; its rate depends on environment, clothing, and body size, so it is used cautiously as one input to the postmortem interval.

postmortem interval

The PMI — the estimated time elapsed since death, gauged by combining the early postmortem changes, decomposition, insect activity, and scene clues; no single change dates death precisely.

decomposition

The progressive breakdown of the body after death (autolysis and putrefaction), beginning with greenish discoloration of the abdomen; its degree is one input to estimating the time since death.

chain of custody

The chronological documentation of everyone who handled, transferred, and stored an item of evidence — proving the item in court is the same one collected and was not altered or substituted.

carboxyhemoglobin

The compound formed when carbon monoxide binds hemoglobin; it imparts the bright cherry-red color seen in the skin and lividity of carbon-monoxide deaths and is confirmed by laboratory testing.

hypoxia

Inadequate oxygen delivery to the body's tissues; carbon monoxide kills by causing hypoxia, occupying hemoglobin sites that would otherwise carry oxygen.

anchoring bias

Relying too heavily on the first piece of information received and failing to adjust as new evidence emerges — a cognitive bias that can distort a death investigation.

autopsy

The systematic external and internal examination of the body by a forensic pathologist to provide objective, evidence-based findings that help establish the cause of death.

vicarious trauma

A lasting change in an investigator's beliefs, worldview, and sense of safety that results from empathetic engagement with the traumatic experiences of others.

compassion fatigue

The emotional exhaustion tied specifically to the cost of caring for, and being exposed to, others' suffering; its positive counterpart is compassion satisfaction.

critical incident stress debriefing

A structured, short-term, confidential group support process used soon after a distressing event for early intervention — not a substitute for professional clinical treatment.

NIJ

The National Institute of Justice, whose guide 'Death Investigation: A Guide for the Scene Investigator' (from the National Guidelines for Death Investigation) is the standard the ABMDI exam is built on.

ABMDI Study Guide FAQ

References

1. 1.American Board of Medicolegal Death Investigators (ABMDI). “Registry Certification (basic).” abmdi.org. ↑
2. 2.American Board of Medicolegal Death Investigators (ABMDI). “Application Process & Eligibility.” abmdi.org. ↑
3. 3.National Institute of Justice (NIJ) / Office of Justice Programs. “Death Investigation: A Guide for the Scene Investigator (2024).” ojp.gov. ↑
4. 4.National Institute of Justice (NIJ). “National Guidelines for Death Investigation.” ojp.gov. ↑
5. 5.National Association of Medical Examiners (NAME). “Forensic Autopsy Performance Standards & Manner-of-Death Classification.” thename.org. ↑
6. 6.Centers for Disease Control and Prevention (CDC). “About Carbon Monoxide Poisoning.” cdc.gov. ↑

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