Death Meaning, Manner, Mechanism, Cause and Time

How Do we Define Death? Is a person with a heartbeat alive even if there is no brain activity ?

How do we define Death? Death is a process not an event –Physiologists; when cells begin to die O 2 levels drop-no Oxygen  no ATP Basic processes of the body fails –Nerves, muscles, organs stop working… Once enough cellular death occurs life cannot restart

Forensic Pathologist Examination of the deceased  Autopsy when the death is: –Sudden –violent –unexplained deaths Investigators will look into –Manner –Cause –mechanism of death Questions sought to answer: –Who is the victim –What injuries are present –When did the injuries occur –Why and how were the injuries produced

Manner of Death 1.Natural Interruption and failure of bodily function resulting from age or disease 2.Accidental Unplanned event 3.Suicidal A person purposely kills oneself 4.Homicidal Death of one person caused by another 5.Undetermined Suicidal or accidental?? –Pills, guns

Time of Death

Estimating Time of Death 1. Rigor mortis-Stiffness of Death 2. Livor mortis: (Lividity)-Color of Death 3. Algor mortis: Body Core Temperature 4. Potassium levels in vitreous humor + Clouding of the cornea 5. Stomach Contents 6. Evidence of Decomposition 7.Insect

Algor Mortis body temperature Normal body temperature is 37 0 C ( F) A body loses heat at a rate of F per hour until the ambient temperature is reached –Rate varies according to environmental temperature Once ambient temperature is reached, you cannot use this method to determine time of death

Question: What are some Factors that would affect Algor Mortis?

Rigor mortis: The stiffness begins 2 hours after death  Oxygen is needed for muscle relaxation.

Rigor Mortis TimeEventAppearance 2-6 hoursRigor begins in headeyelids, Jaws stiffen After 2 hours then center of body stiffens 12 hoursComplete RigorEntire body rigid 15-36Slow loss of rigor, small muscles first Lost in head and neck, last is bigger leg muscles 36-48Rigor disappears, muscles become relaxed

Figure The structure of skeletal muscle

Rigor mortis ? What are some factors affecting Rigor mortis ? 1.Ambient temperature, Cooler the body the slower the onset of rigor 2.Person’s weight Fat stores more oxygen and slow rigor 3. Type of clothing Helps keep the body warm 4.Illness Dies with a fever? What would you expect? Hypothermic? What would you expect? 5.Level of physical activity Struggling before death rigor, What would you expect?

* Lividity -settling of the blood in the lower portion of the body *** Discoloration does not occur in the areas of the body that are in contact with the ground or another object Begins 2 hours after death and permanent after 8 hours Livor mortis

3. Livor mortis

Potassium levels Clouding of the cornea Cornea is the clear covering of your eyes –Becomes cloudy and opaque after death Takes only a few hours after death if eyes are open at death It takes 24 hours if eyes are closed at death.

Digestion provides clues *stomach empties around 4-6 hours after last meal *If NO food is in stomach-how long ago did death occur? *small intestines empties after approx. 24 hours after last meal *large intestines empties after approx after last meal

Stages of Decomp

Stages of Decomposition Initial decay –Corpse appears normal, internal bacterial decay and autolysis begins Putrefaction –Odor of decaying corpse swollen Black Putrefaction –Very strong odor, flesh appears black, gases escape, corpse collapses Butyric Fermentation -drying,cheesy smell Dry Decay –Corpse is dry, further decay slows from lack of moisture

Stages of Decomposition 2 days –Cells autolysis –Greenish purple staining occurs, blood decomposing –Skin takes on Marbled Appearance 4 days –Skin blisters –Abdomen swells with carbon dioxide Due to bacteria in intestines 6-10 days –Corpse bloats with CO2 –Corpse eventually bursts –Fluid begins leaking from openings as cell membranes rupture –Eyeballs liquefy –Skin sloughs off

Forensic entomology Entomology is study of insects Used for a large variety of instances –Insects and human remains –Damage to property for a civil suit –Insects and injuries in abuse cases

Life cycles of insects is important to understand time of death * complete metamorphosis (egg, larva, pupa, adult) Fly larva are called maggots Determining stages will help tell time of death

Complete Metamorphosis

Fly Pupa

Adult fly emerging from pupa

Blowflies are usually the 1 st invader Can lay eggs within 20 minutes of death

Other uses of Insects Can do DNA analysis on the victim ingested by insect Can do toxicological analysis Wound location

Types of Injury Antemortem-before death. Signs of healing Perimortem-near time of death. No healing Postmortem-after death. Discolored (bite marks, crushing)