Death: Meaning, Manner, Mechanism, Cause and Time

Warm UP 10/1 and 10/2 What is a forensic pathologist?

What is a Forensic Pathologist? Specially trained physicians who are often called medical examiners or coroners. They examine the bodies of people who died suddenly, unexpectedly, or violently, and are responsible for determining the time, cause and manner of death.

Determine Time of Death — Livor Mortis livor mortis: Process when body decomposes and blood seeps down and settles into lower parts of body. Lividity : pooling or settling of blood in tissues after death. Begins 2 hours after death becomes permanent after 8. Livor mortis results in the settling of blood in areas of the body closest to the ground (begins immediately on death and continues up to 12 hours). 4

Determine Time of Death —Rigor Mortis Stiffening of the skeletal muscles after death At death, skeletal muscles cannot relax. Without oxygen, calcium accumulates in these muscles. Calcium is used by the body to signal muscle contraction, this accumulation signals the muscles to contract. The muscles become stiff. Rigor mortis starts in the head and works its way down to the legs. 5 5

Determine Time of Death — Livor Mortis Livor mortis can: Determine Time of Death Within 2-8 hours, can press skin and color disappears Factors affecting lividity Ambient temperature, anything that could impede flow of blood to area Reveal the position of the corpse within first 8 hours If on back, blood will pool along backside Reveal if the body was moved If moved, may show dual lividity from first position and then from second position 7

Determine Time of Death —Rigor Mortis 2 -6 hours postmortem (after death), rigor begins in the head 12 hours postmortem, rigor is complete and throughout the entire body 15 -36 hours postmortem, the muscle fibers begin to dissolve, and softening begins (rigor mortis starts to end). 36 -48 hours postmortem, rigor ends and is relaxed throughout the entire body. If the body exhibits rigor only in the head and neck, the time of death is just over 2 hours. If a body has no visible signs of rigor, it probably has been dead less than 2 hours or more than 48. 8 8

Determine Time of Death —Rigor Mortis Factors that affect rigor mortis Ambient temperature (cold = slow rigor) The weight of the body (obesity = slow rigor) The body’s clothing or lack of it Any illness the person had at the time of death The level of physical activity at the time of death Sun exposure Illness – hyperthermia will slow rigor or a fever means high temps and fast rigor 10 10

Determine Time of Death —Algor Mortis Cooling of the body after death In death a body no longer generates warmth and begins to cool down. To find the standard temperature of a corpse, a thermometer is inserted into the liver. Time of death determined by temperature calculations is expressed as a range of time. Normal body temperature is 98.6°F (37°C) Celcius to Farhenheit conversion = (C x 9/5) + 32 = F Farhenheit to Celcius conversion = (F -32) x 5/9 = F 11 11

Celcius to Farhenheit conversion = (C x 9/5) + 32 = F Farhenheit to Celcius conversion = (F -32) x 5/9 = F

Determine Time of Death —Algor Mortis Calculations First 12 hours after death: Body cools 0.78 °C (1.4 °F) per hour After 12 hours after death: Body cools 0.39 °C (0.7 °F) per hour 13 13

Examples What is the temperature loss for someone who has been dead for 12 hours? If a corpse has a temperature of 92.7 °F, how long has the body been dead?

Determine Time of Death —Algor Mortis Now it’s your turn … What is the temperature loss for someone who has been dead for -- 8 hours 15 hours 22 hours How long has a woman been dead if, upon discovery, the temperature of her corpse is -- 92.3 degrees F 89.1 degrees F 34.2 degrees C

Determine Time of Death —Stomach and Intestinal Contents 4-6 hours for stomach to empty contents into small intestine Another 12 hours for the food to leave the small intestine for the large intestine 24 hours for the food to leave the large intestine If undigested stomach contents are present, then death occurred zero to two hours after the last meal. If the small intestine is empty and wastes are found in the large intestine, then death occurred 12 or more hours after a meal. 16 16

Determine Time of Death —Stomach and Intestinal Contents Example – Determine the time of death from the last meal if food is found in the small intestine Answer: Death occurred 4 - 6 hours after the last meal 17 17

Exit Ticket 10/1 and 10/2 A dead woman’s body has a temperature of 33.9 degrees C. Estimate how long she has been dead.

Warm UP 10/3 and 10/4 What is the standard temperature of a living body in degrees F? Degrees C? Why do dead bodies stiffen (rigor mortis)?

Determine Time of Death —Insects Forensic Entomology Forensic Entomologists study insects and their relationships to criminal investigations Within minutes of a death, certain insects arrive to lay their eggs on the warm body. Blowflies are a common example As a corpse progresses through the stages of decomposition, other kinds of insects arrive. 20 20

Determine Time of Death —Insects Life Cycle of Insects Collected from Dead Body Stage Accumulated Time Since Egg Was Laid (Hours) Accumulated Time Since Egg Was Laid (Days) Egg Egg laid minutes after death Larva stage 1 24 1 Larva stage 2 60 2.5 Larva stage 3 96–120 4–5 Pupa 192–288 8–12 Adult 432–576 18–24

The dead body of an elderly gentleman was discovered in an abandoned building. Blowfly pupae were found on the body. A missing person’s report was filed for an elderly gentleman who had wandered away from home just two days before. The body found was similar in age, height, and weight to the missing person. Could this possibly be the same person as the person described in the missing person’s report? Explain your answer.

No, the dead body could not have been the same as the missing man No, the dead body could not have been the same as the missing man. We know this because blowflies enter the pupae stage 8-12 days after the initial eggs were laid. This means that the dead elderly gentleman has been dead for at least 8 days, and therefore could not be the missing man who wandered away 2 days ago.

EXIT TICKET The police received a report about a body found in the woods behind the local shopping center. The forensic investigator collected 5 different types of living insects on the man’s body. It’s important to stress that investigators found all 5 insects alive on the body at the same time. The insects were sent to the forensic entomology lab, where they were raised under similar conditions to those found around the dead body. The following chart describes the life cycles of each of the five different types of insects found on the dead body. How long has the man been dead? Justify your answer. Day Insect 1 2 3 4 5 6 7 8 9 10 Blowfly 1 1 1 1 1 1 1 1 1 0 Species A 0 0 0 0 1 1 1 1 1 1 Species B 0 0 0 0 0 0 1 1 1 0 Species C 0 0 0 0 0 0 0 0 1 1 Species D 0 0 0 0 0 1 1 1 1 1 0 = no evidence of fly species 1 = evidence of egg, larva (maggot) or pupa

Algor mortis calcuations For first 12 hours: (initial temp – final temp) / 1.4 F or 0.78 C For over 12 hours: initial temp – 16.8 F or 9.4 C (new temp – final temp) / 0.39 C or 0.7 F *units for final answer are always in HOURS