Forensics Chapter 4: Traumatic Deaths

Front 1

What are the three ways time of death is estimated?

Back 1

Rigor mortis
Livor mortis
Algor mortis

Front 2

What is Rigor Mortis?

Back 2

Rigor mortis is the stiffening of the muscles following the death of an individual.

Rigor mortis is usually seen about four hours after death. It begins in the head and moves down to the toes. It takes about 12 to 18 hours for the entire body to be affected. At this point it is difficult to move the joints, and they can be broken in the process.

Rigor mortis is caused when actin and myosin filaments in the muscles lock together and stay that way. When a muscle contracts thousands of actin and myosin filaments lock and pull together. The muscle contraction releases when ATP attaches to the myosin heads and force them to release from the actin.

Front 3

What is Livor Mortis?

Back 3

Livor mortis, postmortem lividity or hypostasis is the settling of blood in the lower portion of the body. It causes a purplish red discoloration of the skin. Livor mortis occurs when the heart is no longer circulating the blood and the heavy red blood cells sink through the serum due to gravity.

Livor mortis starts 20 minutes to 3 hours after death. Maximum lividity occurs within 6 to 12 hours. Livisity disappears with decomposition after 36 hours.

Livor mortis is used not only to determine time of death, but also whether a body as been moved. If a body is found face down but the pooling is seen on the back, investigators can determine the body was originally face up.

Front 4

What is Algor mortis?

Back 4

Algor mortis is the reduction of body temperature following death. It is a steady decline until the body matches ambient temperature. The standard rule of thumb is that the body temperature will drop 1.5*C per hour for the first 8 hours.

Front 5

How are traumatic deaths classified?

Back 5

By Truamatic Deaths, Mechanical Deaths, Blunt Truamas, and Firearms.

Traumatic deaths are classified as mechanical, thermal, chemical, or electrical.

Mechanical deaths are further divided into blunt and sharp categories.

Blunt traumas are subdivided into firearm and nonfirearm.

Firearms can be divided into low velocity and high velocity.

Front 6

What are lacerations?

Back 6

Lacerations are injuries produced by blunt instruments.
Lacerations are irregular, tear-like wounds. Ex. pg 46 Figure 4.2

Front 7

What is exsanguination?

Back 7

Exsanguination is the fetal process of complete blood loss, or hypovolemia. It is commonly called bleeding to death or bleeding out.

Exsanguination can occur if a major artery (femoral, brachial, carotid, radial, ulnar) is severed and the bleeding isn’t stopped.
It also can occur from blunt force trauma to the liver, spleen, heart, lungs, or kidneys.

Front 8

What is the most common form of death from a blunt force trauma?

Back 8

Damage to the brain is the most common form of death from blunt force trauma.

Front 9

How are firearm injuries classified?
First & Second
(1-5)

Back 9

The first way that firearm injuries can be classified is by the propellant used. The propellant is used to accelerate the projectile (bullet). The two most common propellants are gunpowder and nitrocellulose (smokeless powder). Smokeless powder is the most common propellant used.

• The second way firearm injuries can be classified is between rifled and smooth bored weapons.

• Rifled weapons fire a single projectile through a barrel that has a shallow spiral pattern made in it. The rifling (spiral pattern) is composed of lands and proves that gives the bullet its spin and also leave a distinctive pattern on it. This patter is what allows a bullet to be matched to the gun that fired it. Common rifled weapons are revolvers, pistols, and rifles.

Front 10

How are firearm injuries classified?
Third, Forth & Fifth
(1-5)

Back 10

The third way the firearm injuries can be classified is with the diameter of the projectile.

• A fourth way that firearm injuries can be classified is by the velocity of the projectile. Hunting rifles and military rifles produces high-speed projectile injuries. The .44 magnum is the only handgun that can produce a high-speed injury.

• A fifth way the firearm injuries are classified is if the wound in penetrating or perforating. A penetrating wound has an entrance point but no exit. A perforating gunshot wound has an entrance and exit point.

Front 11

Another way to classify gunshot wound is the distance the gun was fired from the individual struck. Gunshot wound can be considered contact, near contact, intermediate contact, or distant wounds. Name these three types of gunshot wounds.

Back 11

Contact Wounds
Near contact / and intermediate gunshot wounds
Distance gunshot wounds

Front 12

Explain Contact Wounds.

Back 12

If the barred of the gun is help directly against the skin when fired, the wound is considered a contact would. In contact wounds the gases and heavy metal particulates are blasted into the body along with the bullet. The hot gases char the skin and unburned powder can be found in the wound. Contact gunshot wounds over bone leave a stellate or laceration patter. The wound will have central defect with an abrasion pattern. The wound also may show the imprint of the muzzle. It will also have a bright read appearance due to a reaction between hemoglobin, myoglobin, and carbon monoxide.

Front 13

Explain Near contact/ Intermediate gunshot wounds.

Back 13

In a near contact and intermediate gunshot wounds the barrel is not in direct contact with the skin, but it is close. The entrance wound will have a large central defect with stippling. Stippling or “tattooing” consists of small, reddish orange abrasions to the skin caused by unburned power or small fragments that exit the barrel. Reddish orange stippling is seen when a person is still libing when they are shot. IF the individual is already dead the stippling will be grey or yellowish.

Front 14

Explain Distance gunshot wounds.

Back 14

Distance gunshot wounds have a central hole with scalloped margins. The skin around the wound will also show an abrasion pattern. Stippling isn’t seen in distant wounds. A shot must be fired from under two feet to show stippling.

Front 15

When a gun is fired the force that propels the bullet is the _____ produced when ______ ______ or _______ is burned.

Back 15

When a gun is fired the force that propels the bullet is the gas produced when smokeless powder or gunpowder is burned.

Front 16

The smokeless powder is ignited when...
This causes the _____ in the cap to ignite, subsequently igniting the powder.
The burning of the powder releases....

Back 16

-The smokeless powder is ignited when a small cap on the back, center of the cartilage (bullet) is struck or heated.
-This causes the primer in the cap to ignite, subsequently igniting the powder.

-The burning of the powder releases carbon monoxide, nitrogen dioxide, carbon dioxide, and other gases which propel the cartridge. Heavy metals like lead, antimony, and bismuth are also released. These heavy metals are found in the primer. All of these gases, heavy metals, the bullet, and unburned smokeless powder are all projected from the barrel of the gun. These gasses, heavy metals, and unburned powder only travel a few inches after being projected.

Front 17

What is carbon monoxide and how does it cause death?

Back 17

Carbon monoxide is a colorless, odorless gas. It is produced by the incomplete combustion of carbon containing fuels. Deaths to CO can be accidental, suicidal, or homicidal.

CO kills by asphyxiation. It deprives the brain of oxygens. Oxygen binds to hemoglobin in the blood is transported to all the cells throughout the body. CO starves the cells of oxygen by binding to the hemoglobin preventing oxygen from binding.

Front 18

Discuss electrical trauma.

Back 18

The passage of electricity through the body can cause death through ventricular fibrillation. Ventricular fibrillation is a nonpropulsive (no blood is being propelled) quivering of the heart. It leads to nonresuscitability in minutes.

Ventricular fibrillation is common during low voltage electrocution.

High voltage electrocution doesn’t generally cause ventricular fibrillation. The current is defibrillatory. It causes the heart to go into tetany, sustained contracts. The tetany stops when he circuit is broke and the heart will generally start again with a normal rhythm. High voltage electrocution causes severe burns in a fraction of a second.

Front 19

What are the signs of manual strangulation?

Back 19

Manual strangulation victims have fractures or damage to the larynx, hemorrhage into the strap muscles in the neck, fracture of the hyoid bone, and petechial hemorrhages. Petechial hemorrhages are tiny pinpont red marks often found in the eyes. The hemorrhages occur when increased pressure on the veins in the head causing them to rupture letting blood leak from tiny capillaries. Petechial hemorrhages are a sign of airway obstruction. They are found in manual strangulation, ligature strangulation, and smothering.

Front 20

What is ligature strangulation?

Back 20

Ropes, wires, shoestrings, or other cordlike objects cause ligature strangulation. Ligature strangulation doesn’t cause fracture of the hyoid bone. A furrow in the neck is seen.