Time of Death and Postmortem Changes Overview

Death

Cessation of circulation and irreversible cessation today.

Anoxia

Absence of oxygen in tissues.

Ischemia

Restriction of blood supply to tissues.

Cerebral Anoxia

Brain damage from 4-6 minutes without oxygen.

Hypothermic Resistance

Children can resist cerebral hypoxia for 30 minutes.

Brain Death

Incapable of sustaining respiration and circulation.

Brain Criteria

Legal determination of death using brain function.

Postmortem Changes

Physiochemical changes leading to tissue liquification.

Postmortem Clock

Estimation of time of death based on changes.

Environmental Factors

Temperature, ventilation, and humidity affect postmortem changes.

Body Characteristics

Build and health state influence postmortem phenomena.

Injury Analysis

Survival time and injury details assist in time estimation.

Time of Death Estimation

Cannot be pinpointed; ranges are provided instead.

Window of Death

Interval indicating individual was alive before death.

Reliable Testimony

Witness accounts and documents refine time of death.

Postmortem Cooling

Body temperature declines until reaching ambient temperature.

Normal Body Temperature

Average human body temperature is 98.6°F.

Cooling Rate

Cools 2.0°F to 2.5°F in first few hours.

Slower Cooling

Cools 1°F over next 12 to 18 hours.

Core Temperature Measurement

Preferred for accuracy over skin temperature.

Bernard Knight's Review

Accuracy of body temperature measurements remains low.

Algor Mortis

Postmortem cooling of the body temperature.

Cooling Mechanisms

Three ways body loses heat postmortem.

Clothing Impact

Clothing decreases heat loss rate.

Body Fat Impact

Increased fat reduces cooling speed.

Water Immersion Effect

Cool water increases cooling times.

Children's Cooling Rate

Children cool faster due to body mass ratio.

Hyperthermia

Higher body temperature affecting cooling rate.

Corneal Clouding

Thin film on eyes postmortem; 2-3 hours if open.

Tache Noir

Blackish discoloration in eyes partly open.

Pupil Dilation

Pupils dilate due to muscle relaxation.

Myosis

Pinpoint pupils, may persist in opiate deaths.

Postmortem Lividity

Purplish-blue discoloration from blood settling.

Lividity Timing

Evident as early as 20 minutes postmortem.

Blanching of Lividity

Early lividity can be blanched by compression.

Tardieu Spots

Pinpoint hemorrhages from burst capillaries.

Diagnostic Clue

Unusual lividity discoloration indicates cause of death.

Rigor Mortis

Postmortem muscle stiffness following flaccidity.

Rigor Onset

Becomes apparent within 30-60 minutes postmortem.

Rigor Duration

Maximum stiffness within 12 hours, then subsides.

Muscle Rigidity Order

Smaller muscles stiffen before larger ones.

Rigor Reversibility

Once established, rigor cannot reappear.

Factors Affecting Rigor

Exercise, heat, drugs accelerate or slow rigor.

ATP Hydrolysis

ATP breaks down to ADP, producing lactic acid.

Rigor mortis

Postmortem muscle stiffness due to ATP depletion.

Cadaveric spasm

Clenched fist seen in deaths from tension.

Decomposition

Disintegration of body tissues after death.

Autolysis

Self-dissolution by body enzymes postmortem.

Putrefaction

Decay caused by bacteria and microorganisms.

Putrefactive changes

Dependent on temperature and individual's health.

Green discoloration

Early sign of decomposition on abdominal skin.

Gaseous bloating

Swelling due to gas production in decomposition.

Mummification

Drying of tissues in low humidity environments.

Brownish discoloration

Appearance of mummified skin after drying.

Adipocere

Waxy fat saponification in high humidity.

Subcutaneous fat

Fat layer affected by adipocere formation.

Environmental conditions

Factors influencing decomposition rate and severity.

Skeletonization

Process of bones breaking down over time.

Weathering changes

Slow degradation of bones lasting decades.

Pupillary disparity

Unequal pupil size due to rigor mortis.

Misleading artifacts

Postmortem changes that mimic antemortem injuries.

Destructive environmental factors

Conditions altering appearance of postmortem artifacts.

Sepsis

Infection influencing decomposition speed.

Cocaine ingestion

Substance affecting postmortem changes.

Time of death

Estimation based on decomposition stages.

Anthropophagy

Preying animals/scavengers assaulting human remains.

Postmortem Vegetal Growth

Fungi development on decomposing bodies.

Forensic Entomology (FE)

Study of insects in legal investigations.

Postmortem Interval (PMI)

Time elapsed since death occurred.

Insect Growth Factors

Temperature and environment influence insect development.

Bow Fly Life Cycle

Stages from egg to adult fly.

Egg Stage

Initial stage of bow fly life cycle.

Larval Stages

Development stages before metamorphosis into adults.

Puparial Stage

Transition from larva to adult fly.

Exhumation

Disinterment of buried human remains.

Legal Exhumation Reasons

Autopsy, identity verification, cause of death.

Body Condition Post-Exhumation

Unpredictable variables affect preservation quality.

Preservation Structures

Skeleton, arteries, and teeth aid identification.

Exhumation Disadvantages

Time and embalming affect forensic findings.

Exhumation Process

Legal procedures vary by jurisdiction.

Next of Kin Authority

Family has primary control over exhumation.

Soil Sample Collection

Analyzing soil for chemicals like arsenic.

Embalming Artifacts

Misinterpretation risks from embalming processes.

Civil Litigation Exhumation

Evaluates medical negligence or treatment issues.

Unlawful Burials

Illegal disposal leads to rapid tissue decay.

Animal Activity Evidence

Signs of scavenging near surface burials.

Forensic Team Roles

Includes toxicologists, serologists, and forensic dentists.