Forensic Death Investigation Notes

FORENSIC PATHOLOGIST

  • Conduct autopsies to determine cause, manner, and time of death.

  • Work with investigators and specialists.

AUTOPSY TYPES AND PURPOSES

  • Clinical/Hospital autopsy: Confirms diagnosis, disease extent, treatment effectiveness.

  • Forensic/medico-legal autopsy: Determines cause/manner of death, often in criminal cases.

  • Includes physical exam, review of reports, and documentation.

CRIME SCENE EVIDENCE COLLECTION AT SCENE

  • Evidence: Fingerprints, footprints, weapons, trace evidence, blood.

  • Hand preservation: Paper bags over hands to avoid condensation and preserve trace evidence.

  • Photography: Overall, medium, close-ups with scale; document injuries and negative findings.

  • Identification: Visual confirmation, fingerprints, DNA, dental records, facial reconstruction, especially when decomposition or severe trauma occur.

AUTOPSY DOCUMENTATION AND PREPARATION

  • External exam: Notes on body condition, clothing, physical characteristics (sex, age, weight, height), tattoos, scars, medical interventions, signs of drug use or trauma.

  • Evidence collection: Clothing, fingernail scrapings, hair, buccal swab, swabs from relevant areas, bullets, hand swabs.

  • Internal exam: Y-shaped incision, organ removal/dissection, microscopy for drug abuse, disease, poisoning.

TEETH, DAMAGED TISSUE, AND INJURY CLASSIFICATION

  • Injuries: Abrasions, contusions, lacerations, sharp-force injuries, gunshot wounds.

  • Special signs: Petechiae (strangulation), Stippling/Tattooing (firearm range).

TOXICOLOGY

  • Samples: Blood, urine, bile, stomach contents, vitreous humor, liver, brain matter.

  • Tests: Alcohol, prescription/illicit drugs, poisons.

DETERMINING THE CAUSE OF DEATH

  • Definition: Injury or disease initiating the fatal event.

  • Can be immediate or delayed; distinct from contributing factors.

BLUNT FORCE INJURY

  • Caused by non-sharp objects.

  • Results in abrasion, laceration, contusion (bruising).

  • Can be fatal with minimal external damage; bruises can be difficult to age.

PATTERNED & HIDDEN INJURIES

  • Blunt objects can leave identifiable patterns.

  • Bruises may appear over time, change color, or be internal only.

  • Internal injuries (e.g., concussions) can be fatal without external wounds.

SHARP FORCE INJURIES

  • Caused by knives/sharp tools.

  • Cut: Longer than deep; Stab: Deeper than long.

  • Edges are clean.

DEFENSIVE WOUNDS

  • Found on forearms, hands, or legs; indicate resistance.

  • Absence may suggest unconsciousness, restraint, or surprise.

ASPHYXIA AND OXYGEN DEPRIVATION

  • Types: CO poisoning, strangulation, hanging, smothering.

  • CO poisoning: Carboxyhemoglobin prevents oxygen transport.

  • Soot in lungs/esophagus indicates victim was alive during fire.

GUNSHOT WOUNDS

  • Appearance helps estimate range and angle.

  • Close-range indicators: Stippling, soot, burning.

  • Distant shot: No residue.

  • Suicide often involves contact or very close range.

  • Autopsy tracks projectile path; bullet recovery is critical for ballistics.

SUBSTANCE USE & DEATH

  • Drugs can be direct or indirect causes or contribute to natural death.

  • Toxicological testing is standard; modern techniques detect low levels.

  • Interpretation requires understanding therapeutic/toxic levels and postmortem changes.

MANNER OF DEATH

  • Definition: Circumstances surrounding the fatal event, determined by forensic pathologist.

  • Categories:

    • Homicide: Non-accidental death by another person.

    • Suicide: Intentional self-inflicted death; requires confirmation victim acted alone.

    • Accidental: Unintentional fatal event (e.g., car crash, overdose, drowning).

    • Natural: Death from disease or body deterioration (e.g., heart attack).

    • Undetermined: No clear cause found after full investigation.

ESTIMATING TIME OF DEATH

  • No exact method; uses witness statements, body changes, and environmental data.

  • Provides an approximate window of time.

ALGOR MORTIS

  • Definition: Postmortem body cooling toward ambient temperature.

  • Rate: 1 ext{–} 1.5^\rm{o} ext{F}/ ext{hour} at 70^\rm{o} ext{F} ext{ to } 72^\rm{o} ext{F}.

  • Influenced by ambient temperature, body size, clothing.

LIVOR MORTIS

  • Definition: Blood settles to lowest body parts, skin turns bluish-purple.

  • Begins 20~ ext{min} ext{–} 3~ ext{hrs} after death; fixed around 16~ ext{hrs}.

  • Indicates time of death and if the body was moved.

RIGOR MORTIS

  • Definition: Muscle stiffening after death.

  • Begins within 0 ext{ to } 24~ ext{hrs}, disappears by 36~ ext{hrs}.

  • Influenced by temperature, prior activity, muscle mass.

VITREOUS POTASSIUM LEVELS

  • Measures potassium in eye fluid, which leaks from cells postmortem.

  • Provides rate for time of death estimation, applicable up to 48~ ext{hrs}.

STOMACH CONTENTS

  • Helps narrow down last meal and possible location of death based on digestion rates.

DECOMPOSITION PROCESS

  • Begins when other methods are unreliable.

  • Autolysis: Self-digestion by enzymes.

  • Putrefaction: Bacterial breakdown (bloating, discoloration, gas, smell).

  • Timeline varies by cause of death, temperature, humidity, body composition.

TIME OF DEATH SUMMARY

  • Algor Mortis: 0 ext{–} 24~ ext{hrs}.

  • Livor Mortis: 0 ext{–} 16~ ext{hrs}.

  • Rigor Mortis: 0 ext{–} 36~ ext{hrs}.

  • Vitreous Potassium: Up to ext{\approx} 48~ ext{hrs}.

  • Stomach Contents: Few hours post-meal.

  • Decomposition: Days to months.

FORENSIC ANTHROPOLOGIST

  • Definition: Analyzes skeletal remains to estimate sex, age, ancestry, height, and detect trauma.

  • Bones resist decomposition, useful for older remains; involved in crime scenes, mass disasters, unidentified remains.

RECOVERY OF SKELETAL REMAINS

  • Treat as crime scene; secure area, search, document with photos, tags, sketches (GPS).

  • Tools: Aerial/infrared photography, ground-penetrating radar, metal detectors, cadaver dogs.

DETERMINING SEX

  • Pelvis: Female (wide, circular opening, 90^\rm{o} subpubic angle); Male (narrow, acute subpubic angle).

  • Skull: Male (larger, pronounced brow ridge, strong jaw); Female (smaller features, softer angles).

AGE ESTIMATION

  • 0–21 years: Tooth formation, bone length, epiphyseal fusion, skull fusion (fontanelles).

  • Adults (>21 years): Pubic symphysis wear, sacral surface changes.

ANCESTRY, HEIGHT, FACIAL RECONSTRUCTION

  • Ancestry: Skull shape, orbital size, nasal cavity traits (probabilistic).

  • Height: Long bone measurements and formulas.

  • Facial reconstruction: Recreates face using skull, estimated age, sex, ancestry when other IDs are unavailable.

TOOLS, CAUTIONS & LIMITATIONS IN ANTHROPOLOGY

  • Tools: GPR, aerial photography, cadaver dogs, GPS, clay sculpting, radiology, DNA analysis.

  • Cautions: Skeletons may lack traits, ancestry is probable, traits can overlap; anthropology is probabilistic, not definitive.

FORENSIC ENTOMOLOGIST

  • Definition: Studies insect growth and succession to estimate postmortem interval (PMI) when other methods are unclear.

BLOWFLIES, LIFE CYCLE, AND PMI

  • First arrivals: Blowflies (green/blue), lay eggs within hours, hatch into maggots.

  • Maggot mass: Consume tissue.

  • PMI estimated from oldest developmental stage.

  • Life cycle: Egg (\rightarrow) Larva (3 stages) (\rightarrow) Pupa (\rightarrow) Adult (hours to 1 month).

FACTORS AFFECTING INSECT DEVELOPMENT

  • Environment (temperature, geography, weather), presence of drugs.

  • Estimates depend on contextual environmental data.

INSECT SUCCESSION SUMMARY

  • Blowflies: First 24 hours.

  • Beetles: Later, eat maggots or tissue.

  • Omnivores (ants, wasps): Mid-stage.

WOUNDS, DRUG CLUES, AND INSECTS

  • Insects colonize wounds faster.

  • Maggots on hands/arms may indicate defensive wounds.

  • Maggots can contain traces of drugs; insect tissue can be chemically analyzed.

COLLECTING INSECT EVIDENCE

  • Document/photograph in place, collect from multiple regions, label carefully, preserve for accurate age determination.