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FORENSIC PATHOLOGY

FORENSIC PATHOLOGY. TIME OF DEATH AND DECAY. Manner of Death. Natural: death as a result of age or disease; this is the most common type of death Accidental: caused by unplanned events ( i.e. car accident ) Suicidal: occurs when a person purposefully kills oneself

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FORENSIC PATHOLOGY

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  1. FORENSIC PATHOLOGY TIME OF DEATH AND DECAY

  2. Manner of Death • Natural: death as a result of age or disease; this is the most common type of death • Accidental: caused by unplanned events (i.e. car accident) • Suicidal: occurs when a person purposefully kills oneself • Homicidal: death caused by another person • Undetermined

  3. Cause of Death vs. Mechanism of Death • The cause of death (COD) is the reason someone dies. Examples include heart attack, stroke, drowning, strangulation and hanging. • The mechanism of death describes the specific change in the body that brought about the death. Examples include exsanguination, pulmonary arrest, and cessation of brain function.

  4. Time of Death (TOD) • There are several factors that are used to help determine the time of death • Some of these factors include: • Livor mortis • Rigor mortis • Algor mortis

  5. Livor Mortis • Means “death color” • After death, blood begins to seep out of the tissues and settles in the body parts closest to the ground • The hemoglobin in the red blood cells begins to spill out of the cells and turns purple • The pooling of blood is called lividity, and provides a clue as to how long the person has been dead

  6. Livor Mortis (cont.) • 2 HOURS: lividity begins • 2-8 HOURS: lividity is present but disappears if the skin is pressed • 8 HOURS: lividity becomes permanent

  7. Livor Mortis (cont.) • The ambient temperature will affect the rate of livor mortis: • Heat speeds up livor mortis • Cool temperatures slow it down • Livor mortis is also affected by anything impeding the flow of blood such as the ground, watch, belt, etc.

  8. Examples of Livor Mortis

  9. Rigor Mortis • Means “death stiffness” • 2 HOURS: rigor begins at the head and begins to move down • 12 HOURS: • peak rigor • 36-48 HOURS: • rigor disappears

  10. Rigor Mortis (cont.) • Rigor is caused by contraction of the skeletal muscle • When death occurs, calcium can no longer be kept out of the cell and the muscles contract Skeletal muscle remains in a relaxed state in the absence of calcium. When calcium enters the cell, it triggers the contraction of the muscle. Calcium is actively pumped out of the cell to relax the muscle.

  11. Rigor Mortis (cont.) • Eventually, the muscle cells begin to die • This accounts for the disappearance of rigor • Rigor is affected by the following factors: • Ambient Air Temperature—warm weather speeds up rigor • Body Weight—because fat stores oxygen, it will slow down rigor • Activity Prior to Death—exercise speeds up rigor because it uses oxygen

  12. Rigor Mortis (cont.) • Cadaveric Spasm: occurs at the moment of death if the victim was gripping something when killed • The condition relaxes within a matter of hours, then the normal pattern of rigor mortis begins

  13. Examples of Rigor Mortis Example of Cadaveric Spasm

  14. Algor Mortis • Means “death heat” • When death occurs, the body can no longer maintain its internal body temperature • The body temperature drops at a rate of .78o C every hour for the first 12 hours • After 12 hours, it drops .39o C every hour until it reaches the temperature of the surrounding environment

  15. Decay • Corpses decompose in predictable ways over time and this can help determine the time of death • Black Fermentation • 6-8 Days: • Corpse continues to bloat with CO2 gas causing the chest and abdomen to burst; corpse collapses; flesh appears black • Initial Decay • 2 Days: • Blood decomposition causes green and purplish staining; skin takes on a marbled appearance • Putrefaction • 4 Days: • Skin blisters; abdomen swells with CO2 gas released by bacteria in the intestines; strong odor of decaying flesh

  16. Decay (cont.) • Butyric Fermentation • 8-10 Days: • Fluids leak out of the body openings; eyeballs liquefy and skin slough off • Dry Decay • After 10 Days: • Corpse is almost dry; further decay is very slow from lack of moisture

  17. Examples of Decay in Pig Carcass INITIAL DECAY • Black Fermentation • Putrefaction • Butyric Fermentation

  18. Examples of Decay in Pig Carcass (cont.) • Dry Decay

  19. Human Decay Skin appears black (Black Fermentation) Marbled Skin (Initial Decay) • Skin Sloughs Off (Butyric Fermentation)

  20. Vitreous Humor • As red blood cells breakdown, they release potassium (K+) • The K+ diffuses at a slow but constant rate into the vitreous humor, semi-fluid substance in the eye • A sample of the humor can be tested for the percentage of K+ present to determine the time of death

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