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? Death is a process not an event –Physiologists; when the heart stops beating, the cells begin to die O 2 levels drop Basic processes of the body fails –Nerves, muscles, organs stop working, Stoppage Once enough cellular death occurs life cannot restart

Forensic Pathologist Examination of the deceased, Autopsy Investigations normally are called upon when the death is: –Sudden –violent –unexplained deaths Investigators will look into –Manner –Cause –And 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

Forensic Pathology  Autopsy performed to establish cause of death.  Classifications of the manner of Death *Natural *Accident *Suicide *Homicide *Undetermined

Manner of Death Five ways people die 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

Identify what is the Manner of Death? Why? Case 1: A man with a heart condition is attacked and dies from a heart attack during the assault. Case 2: An elderly woman dies after being kept from receiving proper health care by her son.

Time of Death

Estimating Time of Death 1. Rigor mortis 2. Livor mortis: (Lividity) 3. Algor mortis: Body Core Temperature 4. Potassium levels in vitreous humor + Clouding of the cornea 5. Stomach Contents 6. Evidence of Decompositional Process 7. Presence/absence of purge fluids 8. Drying of the tissue 9. Insect Larval Instars

Algor Mortis Uses body temperature to determine time of death Normal body temperature is 37 0 C ( F) A body loses heat at a rate of C 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? Ambient temperature Wind? Excess body fat? Clothing

Rigor mortis: The medical condition that occurs after death  Results in the shortening of muscle tissue and the stiffening of body parts  Body stays in the position they are in when death occurs Begins within 12 hours and ends after 48 hours  After 48 hours, muscle cells begin to autolyse

Rigor Mortis TimeEventAppearance 2-6 hoursRigor beginseyelids, 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

Figure One hypothesis for how myosin-actin interactions generate the force for muscle contraction (Layer 1)

Figure One hypothesis for how myosin-actin interactions generate the force for muscle contraction (Layer 2)

Figure One hypothesis for how myosin-actin interactions generate the force for muscle contraction (Layer 3)

Figure One hypothesis for how myosin-actin interactions generate the force for muscle contraction (Layer 4)

Rigor Mortis The biochemical cause of rigor mortis is hydrolysis of ATP in the muscle tissue, the chemical energy source required for movement. Myosin molecules devoid of ATP become permanently adherent to actin filaments and muscles become rigid.”

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? 6.Sun exposure, Sun tanner? What would you expect?

Estimating Time of Death 1. Rigor mortis 2. Livor mortis: (Lividity) 3. Algor mortis: Body Core Temperature 4. Potassium levels in vitreous humor + Clouding of the cornea 5. Stomach Contents 6. Evidence of Decompositional Process 7. Presence/absence of purge fluids 8. Drying of the tissue 9. Insect Larval Instars

* Is a settling of the blood in the lower portion of the body ** Causing a purplish red discoloration of the skin. *** Discoloration does not occur in the areas of the body that are in contact with the ground or another object, Livor mortis

3. Livor mortis

Autopsy and time of death cont… Livor mortis: the medical condition that occurs after death and results in the settling of blood in areas of the body closest to the ground –Evident minutes postmortem –8-12 hours (24-36 hours in cooler temps) postmortem- maximum color or “fixed” livor mortis due to hemolysis (blood vessels break down) –May occur antemortem (before death) in slow deaths –Can congest internal organs

Estimating Time of Death 1. Rigor mortis 2. Livor mortis: (Lividity) 3. Algor mortis: Body Core Temperature 4. Potassium levels in vitreous humor + Clouding of the cornea 5. Stomach Contents 6. Evidence of Decompositional Process 7. Presence/absence of purge fluids 8. Drying of the tissue 9. Insect Larval Instars

Potassium levels in vitreous humor + 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. Cornea

Potassium levels in vitreous humor + Clouding of the cornea Vitreous humor is the jelly like fluid found in the eye. –Concentration of potassium increases slowly during first few days Vitreous humor

5. Stomach Contents

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 Dry Decay –Corpse is almost 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

Objective: You will be able to explain how entomology can be used to determine the time of death. Do Now: Read “Forensic entomology” on p. 19 What factors affect the development of insects?

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

Uses Child abuse cases where parents use wasps to punish children Neglect and improper care of wounds of children and elderly Can explain some car accidents or plane crashes (obstructing fuel lines) Analysis of insects on outside of car may lead to where car has been

Uses Affect blood splatter when insects like roaches walk through it and make unusual marks –May also carry blood spot to another part of room which confuses investigators –Fleas and flies feed on blood and leave some behind in their wastes Insects can be used to help determine origin of material like marijuana because insects feed off of it Insects can be used to determine the time of death

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

Complete Metamorphosis

Fly Larvae (maggots)

Fly Pupa

Adult fly emerging from pupa

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

Blowfly The egg is laid in a day by 1 or 2 days a larvae hatches After feeding, larvae leaves body to form a pupa –Pupa cases stay behind so presence and number important –If adult has already emerged then case will look cut open on one end –Used to determine maximum postmortem

Beetle larvae (Coleoptera)

Coleoptera Coleoptera will invade after most of liquid part is gone –Beetle larvae different from fly because it has 3 pairs of legs and fly has none –Dermestid beetles clean bones –Much later in decay process, predaceous beetles will appear to feed on larvae

Predacious beetles

Entomological evidence can also help determine the circumstances of abuse and rape Victims that are incapacitated (bound, drugged, or otherwise helpless) often have associated fecal and urine soaked clothes or bed dressings. This will attract insects that would normally not appear

Movement of body Certain species will lay eggs inside environment, some outside Some species prefer sunlight or shaded environments

Other uses of Insects Can do DNA analysis on the blood that is in the bodies of these insects that they ate Can do toxicological analysis on insects because they may contain poisons in them from eating the person that had poison