Chapter+11+Notes+KC

Kaitlin Cassity 09/04/08 CSI Period 5: p 308-322

Chapter 11 Death: Meaning, Manner, Mechanism Cause, and Time A. General Information & Vocabulary: 1. Death is the cessation, or end, of life. “The irreversible cessation of circulation of blood.” It is a process rather than an instant event. Stages include stoppage (nerves, muscles, organs, and brain stop working) and autolysis (cell breakdown). 2. Autopsy is an examination taken by a medical doctor, specifically a forensic pathologist, to determine the manner, cause, and mechanism of death. 3. Manner of death: The four ways in which a person can die. Causes include natural death, accidental death, suicidal death, and homicidal death (Undetermined a possibility). 4. Natural death: an interruption and failure of body functions resulting from age or disease. This is the most common manner of death. 5. Accidental death: Death caused by unplanned events. 6. Suicidal death: Death occurs when a person purposeful kills oneself, whether by hanging, drug overdose, gunshot, or some other method. 7. Homicide: A death of one person that is caused by another. 8. Cause of death: Reason why someone dies. 9. Mechanism of death: The specific change in the body that brought about the cessation of life. 10. Livor Mortis: Death color as body begins to decompose, and blood begins to pool in the body (lividity). 11. Rigor Mortis: Death stiffness, which is temporary and can be very useful in determining time of death. 12. Algor Mortis: Death heat used to describe the temperature loss in a corpse. 13. Decomposition: Rotting of all tissues and organs, which depends on person’s age, size of the body, and the nature of death. 14. Forensic Entomology: Study in which specialist observes and records data about the environmental conditions and collects insect evidence from victim’s body. 15. Larvae: immature form of animal that undergoes metamorphosis (maggot) 16. Instars/Pupa: the stage in an insect’s life cycle when the larva forms a capsule around itself and changes into its adult form. B. The Manner of Death/Cause and Mechanism of Death 1. It is difficult to determine if the manner of death was a suicide of accidental death. In some cases, the coroner cannot make this determination and marks the manner of death as unknown. 2. Disease, physical injury, stroke, and heart attack can cause death. (Ex (Homicide): shooting, burning, drowning, strangulation, hanging etc.)

C. Time of Death -By establishing a time of death, a suspect may be proved innocent or considered a person of interest. Factors used to approximate the time of death: livor mortis, rigor mortis, algor mortis, stomach and intestinal contents, changes of the eye following death, and stages of decomposition. 1. Livor Mortis: a) As body decomposes, blood seeps down through tissues and settles into lower portions of body. Red blood cells break down and hemoglobin turns purple. This color is visible on the skin wherever blood pools. b) The pooling of blood, lividity, reveals how long the person has been dead. Lividty begins about two hours after death, with discoloration becoming permanent after eight hours. c) If body becomes warmer, lividity takes place at a faster rate. If body left in a cool room, livor mortis is slower. (Must record environmental conditions) d) Reveals position of corpse during the first eight hours of death as well as if body has been moved. 2. Rigor Mortis: a) Starts within two hours of death, starting at head and working way downward. After twelve hours the body is at its most rigid state. After 36 to 48 hours rigor totally disappears and muscles become relaxed. b) Stiffness occurs because the skeletal muscles are unable to relax and remain contracted and hard. Without circulation of oxygen, no oxygen flows through cells and calcium accumulates in muscle tissue. (Remain contracted, restricted) c) Factors which affect rigor mortis and how long it lasts include: ambient temperature, a person’s weight, the type of clothing, illness, the level of physical activity shortly before death, and sun exposure. 3. Algor Mortis: a) When person is alive, the body maintains a constant temperature. In death, body no longer generates heart and begins to cool down. b) To take a corpse’s temperature, investigators insert thermometer in liver, which measures how fast a corpse loses heat and how long ago death occurred. (Approximately one hour after death body cools at rate of .78 degrees C per hour. c) Surrounding air temperature and other environmental factors affect the rate at which body loses heat. (1 degree F per hour in body) 4. Stomach and Intestinal Contents -Takes 4-6 hours for stomach to empty contents into small intestine and another 12 hours for food to leave. By what is found in stomach, can determine when death occurred I relation to last meal of deceased. 5. Changes of the Eye Following Death After death, a thin film is observed within 2-3 hours if eyes were open at death and within 24 hours if covered in death (Potassium accumulates in vitreous humor). 6. Stages of Decomposition: Initial Decay, Putrefaction, Black Putrefaction, Butyric Fermentation, Dry Decay 2 days of death: face becomes discolored, skin takes a marble appearance, cell autolysis occurs, and green and purplish staining occurs from blood decomposition. 4 days of death: skin blisters, abdomen swells with CO2 6-10 days: Corpse bloats as bacteria continue to feed on tissues, abdominal cavities and chest burst and collapse, fluids leak from body openings, eyeballs and tissue liquefy, and the skin sloughs off. D. Entomology a) Within minutes of death, certain insects arrive to lay eggs on warm body, attracted to smells of decomposition. Eggs hatch and feed on tissues. (Blowflies). b) As a corpse progresses through stages of decomposition, other types of insects arrive, including: tiny wasps who lay eggs and produce wasp larvae. c) Mites and beetles feed on dry tissues and hair. d) Temperature, moisture, wind, time of day, season, exposure to elements, and variations among individual insects affect insect development. . e) By using Accumulated Degree Hours, a more accurate estimate of time of death can be made. Insects are collected at crime scene and are raised in laboratory under similar conditions.