investigation of traumatic deaths ch 4 pages 43-58

Investigation of Traumatic Deaths

Ch 4

Pages 43-58

Terminology – Part 1

Mechanism of Death - biochemical and/or physiological abnormality produced by the cause of death which is incompatible with life

Manner of Death – one of the four ways death can be caused; natural, accidental, suicidal, or homicidal.

Liver mortis – the postmortem reddish discoloration of the body due to the settling of red blood cells due to gravity

Algor mortis – the postmortem cooling of the body. Lacerations – injury produced by blunt instruments; characterized by

surface abrasion, bridging vessels, and nerves with irregular margins. Exsanguinations – death after a significant amount (usually half or more)

of blood is lost. (Bleeding to death) Contusion – bruise; leakage of the blood from damaged blood vessels into

tissues. Hematoma – a tumor of blood caused by leakage from damaged blood

vessels; it contains enough blood to form a blood filled space.

Part 2 Handgun – firearm designed to be fired by the hand Shotgun – smoothbore firearm designed to be fired from the shoulder Contact wounds – a skin injury produced by a weapon in contact

with or a fraction of an inch from the skin when discharged. Explosion – sudden conversion of potential energy to kinetic energy

accompanied by physical destruction of the container or structure via a high pressure wave front.

Stippling – disposition of fragments of powder into the skin as the result of a gunshot wound of relatively close range; also called powder tattooing.

Intermediate range gunshot wounds – firearm wound that shows stippling, but no smoke; generally indicates a distance of a few millimeters to a meter from skin to gun muzzle at the time of discharge.

Distant wound – firearm wound that lacks stippling, smoke, or soot. Indicates a distance of 1 meter or more at the time of discharge.

Shored exit wounds – a bullet exit wound that has many characteristics of a distant entrance wound. Caused by the supporting or shoring the skin as the bullet exits.

Yawing – deviation of a bullet from the longitudinal axis of its flight. Ethanol – ethyl alcohol or beverage alcohol found in beer, wine, and liquors. Depressant – drug that reduces excitability and calms a person Stimulant – drug that produces a temporary increase of functional activity or

efficiency Ventricular Fibrillation – uncoordinated non-propulsive quivering of the

heart often produced by heart attack; also by low voltage electrocution. Asphyxia – the interruption of oxygen to the brain. Ligature – a device, similar to a tourniquet, usually of thread or string, tied

around a limb, blood vessel or similar to restrict blood flow.

Introduction

The purpose of investigating a death is to determine its cause and manner. Forensic pathologist

must be able to support his/her conclusions

Cause and Mechanism of Death

1. The Cause of Death is the disease or injury that initiated the lethal chain of events that led to death. The underlying cause

2. The Mechanism of Death is a biochemical or physiological abnormality produced by the cause of death. A contributory factor

3. Injury takes precedence over disease in determining cause of death.

Manner of death

4. The manner of death is defined as the fashion in which the cause of death came to be:Natural (caused solely by disease)AccidentalHomicide } all involve traumaSuicide

Time of Death

5. When a person dies the following can be used to determine time of death: Rigor mortis – stiffening of the muscles due to the

chemical reaction of glycogen (~4 hrs, lasts 24-36 hrs)

Liver mortis – discoloration of the body due to the settling of the red blood cells (w/in min.- becomes fixed in 12 hrs, disappears in 36)

Algor mortis – is the cooling of the body (1.5°C per hour for the first 8 hours at room temp)

Classification of Traumatic Deaths

*Trauma- a body wound or shock produced by sudden physical injury, as from violence or accident.

6. Traumatic deaths may be classified as: -Mechanical -Thermal -Chemical -Electrical

7. Surgeons typically classify trauma as penetrating (stab wound) or non-penetrating (collisions).

Sharp

Blunt

Non-firearm

FirearmLow

High

8. Asphyxia, death caused by interference of oxygen to the brain,can overlap all classes of traumatic deaths.

Ex: mechanical asphyxia – strangulation

Chemical asphyxia – cyanide poisoning

electrical asphyxia - electrocution

Mechanical Trauma 1. Mechanical trauma occurs when applied physical force exceeds

the tensile strength of the tissue to which the force is applied.

Sharp Force Injury Injuries received from sharp implements (knives, swords, axes) Produces incised wounds Most common cause of death is exsanguination (bleed to death)

Blunt Trauma Most common cause of death is damage to the brain Produces lacerations, contusion, and hematomas

Firearm injury Most common suicidal and homicidal wounds in the US Classified based on the type of firearm and the wounds

Other Blunt Force injury Motor vehicle collision, falls, (accidental) Homicidal – lethal head injury

Incised wounds – Sharp force injury

This is a single-edge blade stab wound in which there is a "hilt" mark at the left. The sharp blade edge is at the right. [Image contributed by Todd Grey, MD, University of Utah]

Seen in this clay model is the pattern of a stab wound from a double edge knife on the left and a single edge knife on the right.

Blunt Trauma Wounds – Lacerations, Contusions, Hematomas

Here is a very superficial laceration of the forehead. Note that the skin surface is broken. There are some small tags of skin where the surface was irregularly torn.

Firearm Wounds

Types of Firearms Gunpowder propelled

(rare) Smokeless powder

(nitrocellulose) Handguns Shotguns

Types of wounds Diameter of the projectile or bullet The velocity of the projectile Penetrating (has and entrance

wound, but not exit) Perforating (has an entrance and

an exit wound) Proximity to the gun at time of

discharge Contact Stippling Distant wound Shored exit wounds Yawing

Firearm wounds

This is an contact gunshot entrance wound. Since the barrel contacts the skin, the gases released by the fired round go into the subcutaneous tissue and cause the star-shaped laceration. Note also the grey-black discoloration from the soot, as well as the faint abrasion ring. [Image contributed by Todd Grey, MD, University of Utah]

An abrasion ring, formed when the force of the gases entering below the skin blow the skin surface back against the muzzle of the gun, is seen here in this contact range gunshot wound to the right temple. [Image contributed by Todd Grey, MD, University of Utah]

This is a contact range gunshot entrance wound with grey-black discoloration from the burned powder.

The right diagram illustrates the basic differences between the skin appearance of a contact, close (intermediate), and distant (indeterminant) range gunshot wound. The appearance of the wounding characteristics in the skull is shown in the lower diagram in which there is bevelling of the skull outward away from the direction of origin of the bullet

This is an intermediate range gunshot entrance wound in which there is powder "tattooing" around the entrance site.

With a contact or very close range gunshot wound, it is possible to have blood spatter as well as sooting on the hand of the person firing the weapon.

Chemical Trauma

Deaths from trauma include deaths that result from the use of drugs or poisons

The most common drug – ethanol Longest history of

abuse

Alcohol.. Nervous system

depressant Slows reactions to the

brain At .25 gram percent /

go into coma Eventually breathe so

slowly they pass out

Other drugs of abuse….

Barbiturates, diazepams, and opiates Produce increasing

degrees of coma followed by cessation of breathing

Exceptions: Marijuana – not

known to have produces an overdose death

Cocaine – is a stimulant and may result in seizures, and uncontrolled quivering of the heart

CO Poisoning

Carbon Monoxide Odorless, colorless, explosive gas

Co kills by asphyxiation – cuts off oxygen to the brain

Binds to the hemoglobin 300 times more strongly than oxygen

Blood levels above 20% may prove fatal

cherry red coloration of skin

autopsy specimen showing brain discoloration

Cyanide Poisoning

Interferes with the oxygenation of the brain Available as the sodium or potassium salt

that is used in electroplating and metal polishing

Smells like almonds

Thermal Trauma

Exposure to excessive heat or coldHypothermiaHyperthermia

Diagnoses requires the absence of other causes of death

Thermal burns are localized woundsCause death when complications arise

Electrical Trauma

The passage of electricity through a person may cause death when the heart experiences ventricular fibrillation

Asphyxias

Drowning- death by asphyxiation of water or other liquid Fluid is in the lungs Diatoms may also be

present

Manual strangulation – with the hands

Ligature strangulation – with a rope/cord/wire

Most common findings fracture of the thyroid

cartilage Hemorrhage of the neck

muscles Presence of a furrow in the

neck Petechial hemorrhaging