The Murder Scene: Death and Autopsies

Define Death: "end of life"; "irreversible cessation of circulation of blood"; "cessation of brain activity"

Chemically and Biologically, what happens during death?

- heart stops beating so cells no longer get supply of blood and oxygen
- “aerobic respiration” stops
o chemical process by which oxygen is used to make energy (ATP) from carbohydrates (sugar)

- muscles are made up of 2 types of fibers that work together
o they “lock and unlock” during muscle contraction and relaxation
o controlled by a biochemical pathway within the cells that depends on the presence of oxygen
o high levels of Ca within the cell stimulates muscle contraction
o Ca must be removed from the cell in order to relax
o The lack of oxygen (and lack of energy) makes it impossible to remove the Ca within the cell
o As the levels rise, muscles remain the contracted state “rigor mortis”
o Rigor mortis continues until muscle proteins begin to decompose

Role of a Forensic Pathologist:

- a medical examiner or coroner that relates the study of medicine to the application of the law

Questions to answer:
1. Who is the victim
2. What injuries are present
3. When did the injuries occur
4. Why and how were the injuries produced

Manner of Death: the ways a person can die
After an autopsy is performed, the cause of death is classified into 1 of 5 categories:
1. natural - interruption or failure of body organs
2. homicide - killing of one person by another
3. suicide - purposeful killing of ones self
4. accident - unplanned event
5. undetermined

Cause of Death: immediate reason someone dies (Ex heart attack, kidney failure)
Mechanism of Death: describes specific change in body that brought cessation of life (heart stopping, loss of blood)

Ex. MoD - Homicide CoD - shooting MoD - loss of blood

Estimating the time of death
Stages of decomposition:

Rigor mortis – a condition immediately following death when the muscles relax and then become rigid
Manifests itself within 24 hrs and disappears within 36 hours

Factors affecting RM
1. Ambient Temperature
2. Weight
3. Type of Clothing
4. Illness
5. Level of Physical Activity
6. Sun exposure

Livor mortis – when the heart stop pumping, blood begins to settle in parts of the body closest to the ground (lividity - pooling of blood in body)
The condition starts almost immediately and continues for about 12 hours
Helps determine if body was moved after death

Algor mortis – process by which the body temperature continually cools after death until it reaches room temperature
- thermometer inserted into the liver
- affected by location and size of body, clothing, and weather conditions
- about 1 hr after death, the body loses heat at about 1-1.5 °F per hour

Determination of K levels in the ocular fluid – K is released into the vitreous humor after death

Amount of food in the stomach
- takes approximately 24 hours for undigested food to release from large intestines after being eaten
1. undigested stomach contents - death 0-2 hours after last meal
2. stomach empty; food in small intestine - death 4-6 hours after meal
3. stomach and small intestine empty; waste in large intestine - death 12 or more hours after meal

Forensic Anthropolgy: Skeletal Detectives

- concerned with the identification and examination of human skeletal remains
- bones undergo slow breakdown processes
- examination of bones can indicate sex, approximate age, race and injury
- can help create facial reconstructions
- used during mass disasters

Forensic Entomology – The scientific study of insects and their relation to criminal investigation

- Used to estimate the time of death when the circumstances surrounding the crime are unknown

- After decomposition begins, blowflies are the first to infest the body

o they lay eggs in the human remains which turn into maggots or fly larvae
o maggots consume human organs and tissue

- Forensic entomologists identify the specific insects present in the body, examine the stage of development of the fly larvae and back calculate the time of death

- the time required for stage development is influenced by geographical location, climate, and weather conditions.