ABPath Forensic Pathology key terms

Purple-red discoloration of dependent skin caused by gravitational settling of blood after circulation stops; it begins within about an hour, becomes fixed after roughly 8 to 12 hours, and can help estimate time since death or suggest body repositioning.

Stiffening of skeletal muscle from depletion of ATP after death, beginning in small muscles of the face and neck and progressing downward, then resolving in the same order over roughly one to two days depending on temperature and exertion.

The estimated time elapsed between death and discovery or examination of a body, inferred from body temperature, livor and rigor, decomposition, entomology, gastric contents, and scene context, each with substantial uncertainty.

Postmortem cooling of the body toward ambient temperature, used with nomograms or measured cooling curves to estimate time since death, though ambient conditions, body habitus, clothing, and airflow limit accuracy.

Small petechial hemorrhages in dependent, congested tissues such as the lower limbs or conjunctivae that develop postmortem from rupture of engorged capillaries; they are not evidence of antemortem trauma.

Pinpoint hemorrhages caused by rupture of small vessels, classically seen in the conjunctivae, face, and oral mucosa in asphyxial deaths and in the pleural or pericardial surfaces in cardiac deaths.

The point at which hypostatic blood staining of tissue becomes permanent and no longer blanches with pressure, generally after about 8 to 12 hours, allowing inference that a body was not moved afterward.

A wound with a circular or oval defect, an abraded margin (abrasion collar), possible soot, powder, or tattooing at close range, and inward-beveled bone; its features help establish range of fire and direction.

A wound typically larger and more irregular than the entrance, often with everted margins, no soot or abrasion collar, and outward-beveled bone; atypical exits can mimic entrances when shored or when the bullet deforms.

A ring of scraped epidermis around a gunshot entrance produced by the bullet indenting and rubbing the skin; it indicates entry and helps distinguish entrance from exit wounds.

Punctate abrasions caused by unburned or partially burned powder grains striking and embedding in skin, indicating a close-range discharge typically within a few tens of centimeters.

Black carbonaceous material deposited on skin or clothing around a gunshot entrance at very close or contact range, which can be wiped away and indicates the muzzle was near the surface.

An exit wound supported against a firm surface such as a wall or belt, producing an abrasion ring that can be mistaken for an entrance wound; recognition prevents misinterpretation of wound direction.

A furrow or abrasion pattern on the neck matching a cord or similar object, whose location, direction, and completeness help distinguish hanging from strangulation and suicidal from homicidal manner.

The distinction between suspension by a ligature with the body's weight as the constricting force and application of force by another person or device; ligature marks, fractures, and scene findings differ.

Tissue damage from impact with a blunt object or surface, producing abrasions, contusions, and lacerations; lacerations show tissue bridging and irregular margins that distinguish them from incised wounds.

Hemorrhage into tissue from rupture of vessels after blunt impact, with skin discoloration whose age can be estimated only loosely; deeper contusions may not appear on the surface.

A tear of tissue from blunt force, characterized by irregular margins, tissue bridging within the wound, and hair bulbs crushed rather than cleanly cut, distinguishing it from sharp-force injury.

A wound produced by a sharp edge, with cleanly cut margins, no tissue bridging, and length greater than depth; sharp-force wounds also include stab wounds and chop wounds.

A penetrating sharp-force injury whose depth usually exceeds its length, with wound dimensions reflecting blade width and thickness; tract examination and clothing defects help estimate the weapon.

A localized collection of blood outside vessels, often from trauma; intracranial hematomas such as epidural, subdural, and subarachnoid types have distinct anatomic locations and clinical implications.

Blood between the dura and arachnoid, usually from tearing of bridging veins; it may be acute or chronic, and dating relies on membrane formation and hemosiderin rather than color alone.

Bleeding into the space between arachnoid and pia, commonly from ruptured berry aneurysm or trauma; extensive basal blood with little trauma suggests aneurysmal rupture.

A pattern of inflicted head injury in infants attributed to violent shaking, classically with subdural hemorrhage, retinal hemorrhage, and encephalopathy; the diagnosis is controversial and requires cautious, multidisciplinary assessment.

Head injury inflicted on a child, encompassing shaking and impact mechanisms, supported by findings such as subdural hemorrhage, retinal hemorrhage, and fractures without adequate accidental explanation.

Estimation of when a contusion occurred from its color, which is unreliable because appearance depends on depth, skin tone, lighting, and resorption; examiners should avoid precise age estimates in testimony.

Death from severe loss of blood, which may result from external wounds or internal bleeding; postmortem findings include pallor, empty chambers, and sometimes paradoxical congestion of organs.

Escape of blood from vessels into tissue or body cavities; its forensic significance depends on location, volume, and whether it occurred before or after death, as judged by vital reactions.

A tissue response that occurs only while circulation is intact, such as hemorrhage, inflammation, or embolization, used to determine whether an injury was sustained before death.

Movement of drugs from organs such as lung, liver, and stomach into blood after death, which can raise central blood concentrations relative to peripheral sites and complicate interpretation.

Fluid of the eye used postmortem to estimate electrolyte concentrations and glucose, because it is relatively isolated from putrefaction; sodium and chloride rise while potassium increases with time since death.

Blood sampled from femoral or other peripheral vessels for drug quantification, preferred over central blood because it is less affected by postmortem redistribution from solid organs.

The classification of how a death arose, conventionally natural, accident, suicide, homicide, or undetermined; it is distinct from cause and from mechanism and is certified on the death certificate.

The disease or injury that initiated the sequence of events leading to death, as recorded on the death certificate; it should be specific rather than a mere mechanism such as cardiac arrest.

The physiologic derangement that produced death, such as exsanguination, arrhythmia, or cerebral edema; it explains the pathway but is not recorded as the underlying cause on the certificate.

Two systems for death investigation: coroners are elected or appointed officials who may lack medical training, while medical examiners are appointed physicians, usually pathologists, with statutory authority to investigate and certify.

The documented, unbroken record of who handled evidence, when, and where, from collection through storage and testing, which establishes that items are what they purport to be and have not been altered.

The written or electronic entries recording each transfer of evidence, including dates, signatures, and conditions; gaps or illegible records can render evidence inadmissible or undermine testimony.

A legal test for admissibility of expert testimony considering whether a method is testable, peer reviewed, has known error rates, and is generally accepted; it replaced stricter general-acceptance rules in federal courts.

Opinion evidence offered by a witness with specialized knowledge to help the court understand technical matters, subject to qualification and admissibility standards and to limits on the basis of the opinion.

The application of skeletal biology to identify remains and interpret trauma, including estimation of sex, age at death, stature, and ancestry, and analysis of perimortem bone injury.

Bone breakage occurring around the time of death, indicated by fresh fracture surfaces, hinging, and lack of healing; distinguishing it from postmortem breakage is essential in skeletal trauma analysis.

The use of dental evidence in legal matters, chiefly identification through dental records and comparison of restorations, and analysis of bite marks, which is increasingly viewed with caution.

Comparison of patterned injuries to a suspect's dentition; it has been criticized for weak scientific basis, and courts increasingly restrict it, so conclusions should be conservative and carefully documented.

Analysis of highly variable genetic markers, such as short tandem repeats, to compare biological samples; interpretation depends on sample quality, contamination control, and statistical estimates of match probability.

Postmortem breakdown of tissue by autolysis and microorganisms, progressing through discoloration, bloating, and skeletonization, with rate strongly influenced by temperature, humidity, and scavengers.

Use of insect colonization and development to estimate time since death, especially when remains are found outdoors; species succession and larval stage provide minimum postmortem interval estimates.

Death from carboxyhemoglobin impairing oxygen delivery, classically producing cherry-red lividity and skin, though this sign is inconsistent; blood saturation measurement confirms exposure.

Impaired oxygen delivery or utilization leading to death, with causes including airway obstruction, neck compression, drowning, and chemical exposure; findings are often subtle and nonspecific.

Death from submersion with impaired respiration, diagnosed largely by circumstances and exclusion; autopsy findings such as foam, water in the stomach, and diatom testing are supportive but not definitive.

Tissue damage from heat or cold, including burns and charring; vital signs such as soot in the airway or elevated carboxyhemoglobin help establish that a fire victim was alive when burned.

Death from electrical current, which may leave characteristic entry and exit burns or no visible marks; arrhythmia is a common mechanism and autopsy may be unrevealing.

Completion of the medical portion of the death certificate, recording cause and manner, with referral to the medicolegal authority for deaths that are violent, unexpected, or unattended.

Systematic inspection and documentation of the body surface, including wounds, scars, and identifying features, with photography and measurement, before internal dissection.

Dissection and inspection of body cavities and organs, with sampling for histology and toxicology, to identify natural disease and trauma and to correlate with external findings.

Microscopic examination of tissue sections, used to characterize disease, date injuries through inflammation and repair, and detect findings invisible grossly.

Practices protecting personnel from bloodborne and airborne pathogens and chemical hazards, including standard precautions, sharps care, ventilation, and appropriate personal protective equipment.

Systematic collection and analysis of death and injury data to detect trends, clusters, and emerging hazards, informing prevention and policy rather than individual case resolution.