Meaning, Manner, Mechanism, Cause and Time Death Meaning, Manner, Mechanism, Cause and Time

Is a person with a heartbeat alive even if there is no brain activity? 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 O2 levels drop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 Natural Accidental Suicidal Homicidal Undetermined death resulting from age or disease Accidental Unplanned event Suicidal Intentionally killing oneself Homicidal Death of one person caused by another Undetermined Suicidal or accidental?? Pills, guns

Cause and Mechanism Cause of death Reason someone dies: Heart attack, gunshot, infection, disease Mechanism of Death-body failure Loss of blood (exsanguination) Loss of oxygen (asphxia)

Time of Death

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

Algor Mortis body temperature Normal body temperature is 370C (98.60F) A body loses heat at a rate of 1.40F per hour until the ambient temperature is reached (Rate varies) 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. 11 11

Rigor Mortis Time Event Appearance 2-6 hours Rigor begins in head eyelids, Jaws stiffen After 2 hours then center of body stiffens 12 hours Complete Rigor Entire body rigid 15-36 Slow loss of rigor, small muscles first Lost in head and neck, last is bigger leg muscles 36-48 Rigor disappears, muscles become relaxed

Figure 49.31 The structure of skeletal muscle 13

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

Livor mortis * 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 Dual lividity-indicates a change in position prior to becoming fixed

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. 48-72 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 Bone and Hair. (without water, limited bacterial action)

Stages of Decomposition 2 days Cells autolysis-cell death 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 25

Fly Pupa                                          26

Adult fly emerging from pupa                                           27

Blowflies are usually the 1st invader                                           Can lay eggs within 20 minutes of death                                 28

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,bones break easier(bite marks, crushing)