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Practice Exams

Module 7.16: Forensic Medicine & Pathology Basics

Introduction

While criminalists analyze physical evidence in the crime laboratory, forensic pathologists examine the body itself to determine the cause and manner of death. Forensic Medicine (also called Legal Medicine) is the application of medical knowledge to legal questions, particularly in cases of violent, sudden, or suspicious deaths. The forensic pathologist performs the autopsy (also called necropsy or post-mortem examination) and provides expert testimony in court. Understanding the basics of forensic pathology is essential for criminologists who work closely with medico-legal officers in death investigations.

Key Learning Objectives:

  • Define Forensic Medicine and Forensic Pathology
  • Differentiate between cause, manner, and mechanism of death
  • Understand the role and procedure of an autopsy
  • Learn methods for estimating time of death
  • Identify types of wounds and injuries

I. Forensic Medicine vs. Forensic Pathology

A. Forensic Medicine (Legal Medicine)

  • Definition: The broad application of medical and paramedical sciences to resolve legal issues.
  • Scope: Includes all medical-legal matters such as:
    • Death investigation
    • Clinical examination of living victims (e.g., rape, physical injuries)
    • Medical malpractice
    • Fitness for duty examinations
    • Age determination
    • DNA paternity testing

B. Forensic Pathology

  • Definition: A subspecialty of forensic medicine that focuses specifically on determining the cause and manner of death through the examination of the deceased body.
  • The Forensic Pathologist's Role:
    1. Perform autopsies on individuals who died under violent, sudden, suspicious, or unexplained circumstances
    2. Collect trace evidence from the body for the crime laboratory
    3. Determine the cause, manner, mechanism, and estimated time of death
    4. Testify as an expert witness in court

Sa madaling salita, ang Forensic Medicine ay malawak - lahat ng medical applications sa legal matters (death investigation, living victims, malpractice, etc.). Ang Forensic Pathology naman ay specific subspecialty na focused sa death investigation - ang forensic pathologist ay nag-aautopsy ng mga namatay sa violent, sudden, o suspicious circumstances para malaman ang cause at manner of death. Sila ang nag-eexamine ng katawan mismo, hindi ng physical evidence lang!

Board Exam Tip: Forensic Medicine = broad field. Forensic Pathology = subspecialty focused on death investigation and autopsy.

II. Cause, Manner, and Mechanism of Death

Understanding the difference between these three terms is critical in death investigation.

A. Cause of Death

  • Definition: The injury or disease that directly led to the person's death.
  • Examples:
    • Gunshot wound to the head
    • Stab wound to the heart
    • Myocardial infarction (heart attack)
    • Acute hemorrhage

B. Manner of Death

  • Definition: The circumstances surrounding the death - the "how" or "why" the cause of death came about.
  • The Five Manners of Death:
    1. Homicide: Death caused by the intentional actions of another person
    2. Suicide: Death caused by the intentional actions of the deceased
    3. Accident: Death caused by unintentional injury
    4. Natural: Death caused by disease or natural bodily processes
    5. Undetermined: Insufficient evidence to classify the manner

C. Mechanism of Death

  • Definition: The specific physiological derangement or biochemical disturbance that caused the cessation of life.
  • Examples:
    • Exsanguination (bleeding to death)
    • Cardiac arrest
    • Respiratory failure
    • Cerebral hypoxia (lack of oxygen to the brain)

Eto ang tatlong importante: (1) CAUSE of Death - yung injury o sakit na DIRECTLY nag-cause ng death (gunshot wound, stab wound, heart attack); (2) MANNER of Death - yung "circumstances" kung PAANO nangyari ang cause (Homicide, Suicide, Accident, Natural, Undetermined) - ito ang 5 manners; (3) MECHANISM of Death - yung specific physiological process na nag-stop ng buhay (exsanguination/bleeding out, cardiac arrest, respiratory failure). Example: CAUSE = gunshot wound to chest; MANNER = homicide; MECHANISM = exsanguination (dumugo hanggang mamatay).

Board Exam Tip: Memorize the 5 Manners of Death: Homicide, Suicide, Accident, Natural, Undetermined (HSANU). Very common exam question!

III. The Autopsy (Post-Mortem Examination)

A. Definition and Purpose

  • Autopsy (from Greek: "to see for oneself") is the systematic external and internal examination of a dead body to determine the cause, manner, and mechanism of death.
  • Types:
    1. Medico-Legal Autopsy: Ordered by legal authority in cases of violent, sudden, or suspicious death (e.g., homicide, suicide, accident)
    2. Clinical/Hospital Autopsy: Performed at the request of the family or hospital to determine disease processes (non-legal)

B. The Autopsy Procedure

  1. External Examination:

    • Document physical characteristics (height, weight, age, identifying marks)
    • Photograph the body and all injuries
    • Collect trace evidence (fibers, hairs, gunshot residue, fingernail scrapings)
    • Document wounds, bruises, and any signs of trauma

  2. Internal Examination:

    • The body is opened using a Y-shaped incision
    • Each organ is examined, weighed, and sampled
    • Tissue samples are preserved for microscopic examination (histology)
    • Biological fluids (blood, urine, vitreous humor) are collected for toxicology

  3. Documentation:

    • Detailed written report
    • Photographs and diagrams
    • Toxicology and histology results

C. Evidence Collected During Autopsy

  • Trace Evidence: Hair, fibers, gunshot residue, paint chips
  • Biological Evidence: Blood, semen, saliva for DNA analysis
  • Ballistic Evidence: Bullets, bullet fragments
  • Toxicological Samples: Blood, urine, vitreous humor, liver tissue

Ang Autopsy o Post-Mortem Examination ay systematic examination ng patay na katawan para malaman ang cause, manner, at mechanism of death. May Medico-Legal Autopsy (for violent/suspicious deaths - ordered by legal authority) at Clinical Autopsy (for medical purposes - requested by family/hospital). Ang procedure: (1) External Exam - document physical features, photograph injuries, collect trace evidence; (2) Internal Exam - Y-shaped incision, examine and weigh organs, collect samples for toxicology and histology; (3) Documentation - detailed report, photos, lab results. Maraming evidence ang nakukuha sa autopsy - trace evidence, biological evidence, bullets, toxicology samples!

Board Exam Tip: Medico-Legal Autopsy = for violent/suspicious deaths (legal authority orders). Clinical Autopsy = for medical purposes (family requests).

IV. Estimating Time of Death (Post-Mortem Interval)

Determining when a person died is crucial for establishing timelines and alibis. Several methods are used, often in combination.

A. Algor Mortis (Body Cooling)

  • Principle: After death, the body cools from normal body temperature (37°C or 98.6°F) to ambient temperature.
  • Rate: Approximately 1-1.5°C per hour during the first 12 hours (varies with body size, clothing, environment)
  • Limitation: Affected by many factors (ambient temperature, clothing, body composition)

B. Rigor Mortis (Muscle Stiffening)

  • Principle: After death, chemical changes cause muscles to stiffen.
  • Progression:
    • Onset: 2-4 hours after death (starts in small muscles like jaw and eyelids)
    • Full rigor: 8-12 hours (entire body is stiff)
    • Disappearance: 24-48 hours (muscles relax as decomposition begins)
  • Limitation: Affected by temperature, physical activity before death, and body composition

C. Livor Mortis (Lividity/Hypostasis)

  • Principle: After the heart stops, blood settles to the lowest parts of the body due to gravity, causing purple-red discoloration.
  • Progression:
    • Onset: 30 minutes to 2 hours after death
    • Maximum: 8-12 hours
    • Fixed: After 8-12 hours, lividity becomes "fixed" and won't blanch when pressed
  • Forensic Value: Can indicate if a body was moved after death (lividity in areas not in contact with the ground suggests repositioning)

D. Other Methods

  • Stomach Contents: Can estimate time of last meal (food takes 2-6 hours to leave the stomach)
  • Decomposition Stages: Used for longer post-mortem intervals
  • Entomology: Study of insect activity on the body (very accurate for days to weeks)
  • Vitreous Potassium: Chemical analysis of eye fluid (accurate for first 2-3 days)

Ang estimation ng Time of Death o Post-Mortem Interval (PMI) ay importante para sa timeline at alibis. May tatlong major signs: (1) Algor Mortis - pag-cool ng body, approximately 1-1.5°C per hour sa first 12 hours; (2) Rigor Mortis - muscle stiffening: onset 2-4 hours, full rigor 8-12 hours, disappears 24-48 hours; (3) Livor Mortis - blood settling to lowest parts (purple-red discoloration): onset 30 min-2 hours, maximum 8-12 hours, fixed after 8-12 hours. May other methods din: stomach contents, decomposition, insects (entomology), vitreous potassium. Para maalala ang sequence: ALGOR (cooling) → RIGOR (stiffening) → LIVOR (discoloration)!

Board Exam Tip: Remember the timeline: Livor onset first (30min-2hrs), then Rigor onset (2-4hrs), both maximum at 8-12hrs. Rigor disappears at 24-48hrs. Very testable!

V. Types of Wounds and Injuries

A. Gunshot Wounds

  • Entrance Wound: Usually smaller, with abrasion ring, may have powder burns or stippling if fired at close range
  • Exit Wound: Usually larger and more irregular, no powder burns
  • Contact Wound: Muzzle pressed against skin - distinctive star-shaped wound with soot in wound

B. Stab/Incised Wounds

  • Stab Wound: Depth greater than length (penetrating)
  • Incised Wound: Length greater than depth (slicing/cutting)
  • The wound can indicate weapon characteristics: Length, width, single or double-edged blade

C. Blunt Force Trauma

  • Contusion (Bruise): Bleeding into tissue without break in skin
  • Abrasion (Scrape): Superficial injury to skin surface
  • Laceration: Tearing of skin and tissue (irregular wound edges)
  • Fracture: Break in bone

D. Asphyxia (Lack of Oxygen)

  • Strangulation: Compression of neck by ligature (rope, wire) or hands
  • Suffocation: Obstruction of airways (smothering, choking)
  • Drowning: Inhalation of water
  • Signs: Petechial hemorrhages (pinpoint red spots) in eyes and face

May apat na major types ng wounds: (1) Gunshot Wounds - entrance wound (smaller, abrasion ring, powder burns if close range) vs exit wound (larger, irregular, no powder); contact wound ay star-shaped; (2) Stab/Incised Wounds - stab ay depth > length (penetrating), incised ay length > depth (slicing); (3) Blunt Force Trauma - contusion (bruise), abrasion (scrape), laceration (tearing), fracture (broken bone); (4) Asphyxia - strangulation, suffocation, drowning - may petechial hemorrhages sa eyes/face. Ang characteristics ng wound ay nag-iindicate ng weapon type at circumstances!

Board Exam Tip: Entrance vs Exit Wound: Entrance = smaller + abrasion ring + powder burns (if close). Exit = larger + irregular + NO powder burns.

VI. The Medico-Legal Officer in the Philippines

In the Philippines, the medico-legal officer is a physician who conducts autopsies and examines living victims in cases with legal implications.

A. Where They Work

  • PNP Crime Laboratory - Medico-Legal Division
  • National Bureau of Investigation (NBI) - Medico-Legal Division
  • Public Attorney's Office (PAO) - Forensic Laboratory

B. Their Responsibilities

  1. Conduct autopsies in cases of violent, sudden, or suspicious death
  2. Issue Medico-Legal Certificates for living victims (rape, physical injuries)
  3. Exhume bodies when necessary
  4. Testify as expert witnesses in court
  5. Collect and preserve evidence from bodies

Ang Medico-Legal Officer sa Pilipinas ay physician na nag-conduct ng autopsies at nag-examine ng living victims sa legal cases. Sila ay nagtatrabaho sa PNP Crime Lab, NBI, o PAO Forensic Lab. Ang kanilang responsibilities: autopsy ng violent/suspicious deaths, pag-issue ng Medico-Legal Certificates (for rape, physical injuries cases), exhumation, expert testimony sa court, at evidence collection. Sila ang kasama ng investigators sa death scenes!

Conclusion

Forensic Medicine and Pathology form the medical pillar of death investigation. While criminalists examine the physical evidence at the crime scene and in the laboratory, the forensic pathologist examines the body itself—the most important piece of evidence in a homicide. By determining the cause, manner, and time of death, and by carefully documenting injuries and collecting trace evidence from the body, the medico-legal officer provides crucial information that helps investigators reconstruct events, identify suspects, and bring justice to victims. For criminologists, a solid understanding of forensic pathology principles is essential for effective collaboration with medical examiners in the field.

Board Exam Review Summary:

  1. Cause vs Manner vs Mechanism

    • Cause = what killed (gunshot, stab wound)
    • Manner = circumstances (Homicide, Suicide, Accident, Natural, Undetermined)
    • Mechanism = physiological process (exsanguination, cardiac arrest)

  2. 5 Manners of Death: HSANU - Homicide, Suicide, Accident, Natural, Undetermined

  3. Time of Death Signs:

    • Algor Mortis = cooling (1-1.5°C/hour)
    • Rigor Mortis = stiffening (onset 2-4hrs, full 8-12hrs, disappears 24-48hrs)
    • Livor Mortis = blood pooling (onset 30min-2hrs, fixed 8-12hrs)

  4. Gunshot Wounds:

    • Entrance = smaller + abrasion ring + powder burns (if close)
    • Exit = larger + irregular + NO powder burns

  5. Autopsy Types:

    • Medico-Legal = violent/suspicious deaths (legal authority)
    • Clinical = medical purposes (family request)

Mnemonic: "CALM RiLi" = Cause-Algor-Livor-Manner-Rigor-Lividity (key concepts in death investigation)