DEATH-BLOOD Copy

Understanding Death in Forensic Science

Definition of Death

  • Death: The irreversible cessation of life, particularly the circulation of blood.

  • Coroner's Role: Investigates human deaths, determines manner of death, issues death certificates, and maintains death records.

    • Can’t conduct autopsies unless directed by a pathologist.

Manner, Mechanism, Cause, Time of Death

  • Manner of Death: Categorized methods of how death occurs.

    • Types:

      • Natural

      • Accidental

      • Suicidal

      • Homicidal

      • Undetermined

  • Mechanism of Death: Specific body changes leading to death. Examples:

    • Pulmonary arrest

    • Blood loss

    • Cessation of brain function

  • Cause of Death (COD): The actual reason behind the death, such as:

    • Natural (e.g., heart attack)

    • Homicidal (e.g., shooting)

    • Accidental (e.g., drowning)

    • Suicidal (e.g., overdose)

Post-Mortem Changes

Rigor Mortis

  • Rigor Mortis: Stiffening of skeletal muscles after death.

    • Begins within 2 hours and is fully developed by 12 hours after death.

    • Lasts about 36 hours, moving from head to legs.

  • Factors Affecting Rigor Mortis:

    • Ambient temperature

    • Clothing

    • Physical activity before death

    • Illness

Algor Mortis

  • Algor Mortis: Cooling of the body.

    • Body cools at approximately 1.4°F per hour until reaching ambient temperature (around 70°F).

Livor Mortis

  • Livor Mortis (Lividity): Blood pooling in the body post-mortem, providing clues on death timing and positioning.

    • Becomes permanent about 8 hours after death.

Stages of Decay

  1. Initial Decay (Fresh Stage): Occurs within the first 2 days, primarily internal changes.

  2. Putrefaction: Notable for changes in odor, typically between the 3rd and 8th days.

  3. Black Putrefaction: Flesh blackens, lasts about 20 days; insects infest the body.

  4. Butyric Fermentation: Dehydration, formation of "grave wax," soft tissues diminish.

  5. Dry Decay/Skeletonization: Remaining bone tissue; further decay slows due to lack of nutrition.

Blood and Its Analysis in Forensics

Blood Components

  • Red Blood Cells (Erythrocytes): Carry oxygen and carbon dioxide; contain hemoglobin.

  • White Blood Cells (Leukocytes): Fight infection; vital for immune response.

  • Platelets (Thrombocytes): Important for blood clotting.

Blood Typing and Clotting

  • Blood evidence analysis can determine connections to crime scenes, using blood type as class evidence.

  • Discovery of blood types by Dr. Karl Landsteiner in 1900.

Blood Spatter Analysis

  • Offers insights into the crime scene, determining direction, point of impact, and more.

  • Key Patterns:

    • Passive Drops: Circular drops falling straight down at 90°.

    • Arterial Spurts: Patterns indicating the pumping action of the heart.

    • Trails and Smears: Indicate movement of injured victims.

Techniques in Crime Scene Investigation

  • Analytical methods to uncover hidden blood:

    • Luminol: Glows in the presence of blood; detects traces even after cleaning.

  • Processing Blood Stains:

    • Chemical tests like Kastle-Meyer to confirm blood presence.

Conclusion

Understanding the principles of death, decay stages, and blood analysis is crucial in forensic science, providing valuable insights for criminal investigations.