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Time of Death:

Time of Death: . During an autopsy, the forensic examiner wants to determine when the person died. . Time of death can: Prove innocence based on time and place or add interest. Many factors are used to approximate the time of death. Livor Mortis: Lividity (Purple color)

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Time of Death:

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  1. Time of Death: During an autopsy, the forensic examiner wants to determine when the person died. Time of death can: Prove innocence based on time and place or add interest

  2. Many factors are used to approximate the time of death • Livor Mortis: Lividity (Purple color) • Rigor Mortis (stiffness) • Algor Mortis (loss of temp) • Environment: ambient temp,humidity, wind • Clothing • Exercise • Weight • Decomposition of Eye?

  3. Livor Mortis means death color As a body decomposes, blood seeps down through the tissues and settles into the lower parts of the body. RBC begin to break = spilling contents Hemoglobin turns purple when outside of RBC Purple color is visible on skin where blood pools

  4. Lividity:the pooling of blood provides a clue as to how long the person has been dead First begins 2 hrs after death Discoloration becomes permanent after 8 hours If death occurred between 2 and 8 hrs lividity will be present but if the skin is pressed the color will disappear After 8 hours, lividity remains Ambient Temperature at death impacts the time it takes for lividity to set in Faster = hot Slower = cold **** important to note environmental condition surrounding body

  5. Livor mortis provides clues in addition to time of death Position of corpse in the first 8 hours Reveal if the body has been moved Dual lividity: Ex. Person died sitting in a chair: lividity on back of thighs, buttocks and bottom of feet (in first 8 hours) Then the corpse is moved face down on the floor: lividity on face, chest and abdomen and front surface of legs Tight watches or belts affect livor mortis = impede blood flow

  6. Rigor Mortis:temporary death stiffness • Starts within 2 hours • Starts in the head working down to the legs • After 12 hours, most rigid state • After 24-36 hours gradually lose stiffness due to acid formation (degradation) • Rigidity in face and neck: recent (2 hrs) • Body is rigid but not in face then over 15 hrs • If a body shows no rigor death occurred less than 2 hours or more than 48 Rigor also depending on the condition of the body at death and on factors in the atmosphere, particularly temperature.

  7. Molecular chemistry - STIFF • Stiffness = • level of ATP dropping. • 2. myosin binds to actin and the muscles contract. • 3. However, with no ATP to reset the crossbridges and release the myosin • 4. Due to Ca2+ accummulation

  8. Muscles eventually relax when apoptosis occurs (autolysis) Cell dissolves

  9. Many factors affect When rigor mortis sets in and how long it lasts • Ambient temperature: cooler = slower • Weight: body fat stores extra O2 slows down rigor • Type of clothing: s keep body warm = accelerates rigor • Illness: fever: accelerates rigor, hypothermia: slower • Level of physical activity shortly before death: exercise, struggling speeds up rigor a. body temp b. less O2 c. increase in lactic acid • Sun exposure: increase rigor

  10. Algor mortis: “death heat” • Temperature loss in a corpse • Insert a thermometer into the corpse’s liver • ~ 1 hr after death • Body cools at a rate of 0.78 oC (1.4oF) per hour • ~ After the first 12 hours • Body cools at a rate of 0.39 oC (0.7oF) per hour • Continues until reaches ambient temp of enviro. • ~ Environment affects rate of temp loss as well • Temp, Wind, excess body fat, clothing Rule of thumb estimate: lose 1 degree/hour for a range

  11. Stomach and Intestinal Contents • 4 – 6 hours for the stomach to empty contents into S.I. • Another 12 hours for food to leave the S.I. • ~24 hours for a meal to be eaten and undigested food leaves the L.I. • Undigested contents in stomach: death <2 hours after last meal • Stomach is empty , food in S.I: death at least 4 – 6 hours after meal • Empty SI but wastes are in L.I. then death occurred > 12 hours

  12. There is no scientist in the world like Dr. Bill Bass. A pioneer in forensic anthropology, Bass created the world's first laboratory dedicated to the study of human decomposition—three acres of land on a hillside in Tennessee where human bodies are left to the elements. His research at "the Body Farm" has revolutionized forensic science, helping police crack cold cases and pinpoint time of death. But during a forensics career that spans half a century, Bass and his work have ranged far beyond the gates of the Body Farm. In this riveting book, the bone sleuth explores the rise of modern forensic science, using fascinating cases from his career to take readers into the real world of C.S.I. http://www.jeffersonbass.com/

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