Wounding

Question 1

What is Wound Ballistics?

Answer 1

Wound ballistics can be considered a subdivision of terminal ballistics Which deals with the motions and effects of projectiles in tissue.

Question 2

The extent of injury from a bullet is attributable to:

Answer 2

1. The mechanical shredding and crushing of tissue by the bullet as it perforates the tissue.
2. Shearing, compression and stretching injuries to the tissue due to temporary cavity formation.
3. Secondary issues due to the breakup of the bullet
4. The nature of the tissue perforated by the bullet
5. The length of the wound track

Question 3

Temporary Cavity

Answer 3

A cavity which is formed when the kinetic energy of a projectile is transferred to the surrounding tissue causing it to expand outwardly.

Question 4

How long until the cavity collapses ?

Answer 4

The cavity collapses after a few seconds and is again filled with surrounding tissue and fluid.

Question 5

The are the factors that affect the size and shape of temporary capvity

Answer 5

• Nature of the bullet
• The amount of kinetic energy lost by the bullet in its path
• How rapidly the energy is lost
• The elasticity and cohesiveness of the tissue

Question 6

What is not a significant TC in wounds caused by which firearm?

Answer 6

The temporary cavity is not as significant in wounds caused by handgun bullets as with rifle bullets.

Question 7

How does the organ the projectile hit effect the temporary cavity?

Answer 7

No matter how large the temporary cavity is, it will have little or no effect unless it forms in an organ sensitive to injury from such a cavity (eg. liver vs muscle).

Question 8

How doe the location of the wound play a important role in the severity of the injury.

Answer 8

Specific organs like elastic tissue such as muscle or the lung are more resistant to stretch damage as opposed to solid organs such as the liver.

Question 9

How does kinetic energy determine the size of the temporary cavity?

Answer 9

It is the amount of kinetic energy lost in the tissue that determines the size of the temporary cavity and not the total energy possessed by the bullet.

Question 10

What factors that affect kinetic energy lost ?

Answer 10

1. Yaw of the bullet at the time of impact
2. Bullet Characteristics
3. Location of the wound

Question 11

What is the yaw of the bullet?

Answer 11

The yaw of the bullet is the deviation of the long axis of the bullet from its line of flight. As soon as the bullet leaves the barrel it begins to yaw or wobble.

Question 12

What physical characteristics of the bullet affect the yaw?

Answer 12

The degree of yaw of a bullet is determined by its physical
characteristics of the bullet, the rate of twist and the density of the air.

Question 13

How does the gyroscopic spin become insufficent?

Answer 13

Although the gyroscopic spin imparted by the rifling is sufficient the bullet in air, it is insufficient to stabilize the bullet when it enters the body.

Question 14

How is kinetic energy lost in the wound by yawing?

Answer 14

As the bullet begins to yaw, its cross-sectional area becomes larger, the drag forces increases and more kinetic energy is lost in the wound. The sudden increase in the drag force on yawing puts a great strain on the bullet may cause it to break up.

Question 15

What bullet characteristics can influence the amount of kinetic energy lost in the body?

Answer 15

The bullet characteristics such as its calibre, construction and configuration can influence the amount of kinetic energy lost in the body.

Question 16

How does the type of bullet affect kinetic energy in the body?

Answer 16

Expanding bullets, which open up or mushroom in tissue, are more retarded by tissue than round nose bullets and therefore lose greater amounts of kinetic energy in the body.

Question 17

As the bullet deforms what characteristics are affected?

Answer 17

As the bullet begins to deform, the shape and calibre of the bullet play less of a significant role in the amount of kinetic energy lost in the body.

Question 18

What does bullet deformation depend on?

Answer 18

The amount of deformation depends on the construction of the bullet( length, thickness, hardness of the jacket material, hardness of the lead core and the presence of a hollow point) and the bullet velocity.

Question 19

How does the density of the tissue affect the energy lost ?

Answer 19

The denser the tissue then the greater the retardation and greater the energy lost in the body.

Question 20

What parts of the tissues directly affects the amount of kinetic energy lost?

Answer 20

The density, strength and elasticity of the tissue penetrated by a bullet as well as the length of the wound track plays a significant role in determining the amount of kinetic energy lost in the body.

Question 21

How can handguns produce significant damage?

Answer 21

To cause significant damage, a handgun bullet must strike a structure directly.

Question 22

How big can temporary cavities of rifle bullets get?

Answer 22

Temporary cavities created by rifle bullets can reach up to 12.5 times the diameter of the bullet.

Question 23

What effect does expanding cavity walls have, and how does pressure introduce foreign materials?

Answer 23

The expanding walls of the cavity are capable of causing severe damage. Positive and negative pressures alternate in the wound track, resulting in the sucking of foreign matter and bacteria into the track from both the entrance and exit.

Question 24

Where is maximum kinetic energy lost?

Answer 24

Maximum kinetic energy lost occurs at the point where the bullet is in maximum yaw i.e., at a 90 degree angle to the path.

Question 25

How does permanent cavities form?

Answer 25

Less elastic and cohesive structures struck by high velocity bullets results in a permanent cavity approximately the size of the temporary cavity.

Question 26

What is the critical level of kinetic energy and why is it important?

Answer 26

* There is a critical level of kinetic energy loss above which tissue destruction becomes radically more severe. * When a bullet exceeds this level , it produces a temporary cavity that the organ or tissue can no longer contain. When the * Elastic level is exceeded the organ bursts.

Question 27

What is the critical level exceeded for a full metal jacket projectile?

Answer 27

For full metal jacketed bullets this critical level is exceeded when the projectile reach velocities greater than 2625 – 2950 ft/s.

Question 28

What is the critical level exceeded for a soft point or hollow point rifle bullets?

Answer 28

For soft point or hollow point rifle bullets, the the critical level can be reached at lower velocities as a result of the deformation and breakup of the bullets. Therefore, the critical velocity can be 1500 – 2000 ft/s.

Question 29

What are the four categories into which gunshot wounds can be dvided

Answer 29

* Contact Wounds * Near Contact Wounds * Intermediate Wounds * Distant Wounds

Question 30

What is contact wounds?

Answer 30

A contact wound refers to a wound that is created when the muzzle of the firearm is held against the surface of the body at the time of discharge.

Question 31

What are the main types of contact wounds?

Answer 31

These type of wounds can be divided into: *hard, *loose, * angled * and incomplete wounds

Question 32

What substances are deposited in and along the wound tract in contact wounds ?

Answer 32

* Soot * Powder * Vaporized metals

Question 33

What are hard contact wounds?

Answer 33

Hard contact wounds, the muzzle of the weapon is pushed hard against the skin indenting, so that the skin envelopes the muzzle.

Question 34

What are the characteristics of hard contact wounds?

Answer 34

* Seared edges * Edges blackened by soot * Soot around edges cannot be completely removed either by washing or vigorous scrubbing of the wound.

Question 35

What is loose contact wounds?

Answer 35

Loose contact wound is created when the muzzle is held lightly against the skin.

Question 36

What are some characteristics of loose contact wounds?

Answer 36

* Soot deposited around the entrance * Soot can be easily wiped away * Unburnt grains of powder deposited on the skin in the zone of soot

Question 37

What is angled contact wounds?

Answer 37

This type of contact wound, the barrel is held at an acute angle to the skin, so that the entire circumference of the muzzle is not in contact with it.

Question 38

What are the characteristics of angled contact wounds?

Answer 38

* Conspicuous blackened seared area of skin having a circular or oval shape * Less conspicuous larger fan-shaped zone of light grey soot that radiate outward from the gap * Light zone of soot easily washed or wiped away * Unburnt grains of powder deposited around the wound * Blackened seared area on the opposite site of the wound from the muzzle

Question 39

What is incomplete contact wounds?

Answer 39

This type of contact wounds the weapon is held against the skin but because the surface is not completely flat there is a gap between the muzzle and the skin.

Question 40

What are the characteristics of a incomplete contact wounds?

Answer 40

A jet of soot-laden gas escapes from this gap producing an area of seared, blackened skin.

Question 41

What cases are incomplete contact wounds seen?

Answer 41

These types of gunshot wounds are most often seen in self inflicted gunshot wounds of the head due to long arms. In these cases, the zone of blackened and seared skin usually extends downward from the entrance.

Question 42

What are near contact wounds?

Answer 42

Near contact wounds lie in the zone between contact and intermediate range wounds. This type of contact wound the weapon is not held against the skin but a short Distance away.

Question 43

Which of the contact wounds are similar to near contact wounds?

Answer 43

Near contact wound type of contact wound can be difficult to differentiate from Loose contact wound

Question 44

What are the characteristics of near contact wounds?

Answer 44

* Wide zone of powder soot overlying seared, blackened skin * Soot is baked into the skin and cannot be completely wiped away * Small clumps of unburned powder present in seared zones

Question 45

What is near contact angled wounds?

Answer 45

The near contact wound is where the barrel is held at an acute angle with the muzzle a short distance away from the skin.

Question 46

What are the similarities and difference of near contact angled wounds and angled wounds?

Answer 46

Just as in angle contact wounds soot radiates outward from the muzzle creating a circular or irregular shaped blackened seared zone and a light gray fan-shaped. However, unlike angle contact wounds the bulk of the seared blackened zone is on the same side as the muzzle.

Question 47

What is intermediate range wounds?

Answer 47

This type of gunshot wound is one in which the muzzle is away from the body at the time of discharge yet close enough to produce “powder tattooing” .

Question 48

What is powder tattooing?

Answer 48

“powder tattooing” as a result of powder grains being expelled from the muzzle with the bullet creating reddish-brownish punctuate lesions surrounding the entrance wound.

Question 49

What does powder tattooing indicate?

Answer 49

Powder tattooing in an antemortem phenomenon and indicates that the Individual was alive at the time they were shot.

Question 50

How can you tell if a person was dead before they were shot?

Answer 50

If the individual was dead before being shot, even though powder marks may be produced, they will have a moist gray or yellow appearance rather than reddish-brownish.

Question 51

How does powder grains impacts powder tattooing?

Answer 51

Powder tattooing are not “powder burns” as often suggested but are rather created by the impact of powder grains on the skin resulting in punctuate abrasions.

Question 52

What is distant gunshot wounds?

Answer 52

Distant gunshot wounds, the marks produced by the interaction of the bullet and the skin are the only marks present.

Question 53

What is entrance wounds?

Answer 53

An entrance wound is said to be round to oval with a reddish –Brownish margin of abraded skin (abrasion ring).

Question 54

What is another way in which entrance wounds may appear?

Answer 54

A fresh entrance wound may also have a punched-out appearance with no abrasion zone with immediate transition from normal appearing skin to shiny pale dermis (this is often seen in centre fire rifle bullets and high-velocity jackets handgun bullets).

Question 55

What is the main difference between an entrance and exit wound?

Answer 55

Exit wounds are typically larger than entrance wounds

Question 56

Why are Exit wounds are typically larger than entrance wounds?

Answer 56

* The tumbling or yawing of the bullet is accentuated and the bullet may even start to travel base first. * The retardation of the bullet by tissue may cause the bullet to deform. *Steel balls fired in the skin will not tumble like bullets and lose some energy at the time of exit causing a smaller wound than the entrance. * An exiting bullet will be undeformed and with its long axis perpendicular to the skin, creating a perfectly round exit wound. In both these instances it may be indistinguishable from an entrance.

Question 57

What are the characteristics of exit wounds?

Answer 57

These include: * They are typically larger than and/or more irregular than entrance wounds * Do not possess an abrasion rings (exception to this is with shored exit wounds)

Question 58

What are other factors that can be used to differentiae between entrance and exit?

Answer 58

* Once a wound has an abrasion ring that it can be easily identified as an entrance. (With exception of the palm, sole and elbow, these wounds are oval to circular) * With a punched out clean appearance to the margins, totally unlike that of exit wounds. (The exception to this are re-entry wounds.) * In rare instances, a circular punched-out entrance without an abrasion ring is associated with an exit that also has a circular punched out appearance.

Question 59

What are re entry wounds?

Answer 59

Re-entry wounds occur when a bullet perforates one part of the body then Re-entered another part of the body.

Question 60

How are re entry wounds categorised?

Answer 60

Re-entry wounds are typically characterized by a large irregular entrance hole, whose edges a ragged and has a wide, Irregular abrasion ring.

Question 61

What is a cylinder gap?

Answer 61

If a revolver is held parallel to the body at the time of discharge, the jet of gas escaping from the gap between the cylinder and the barrel (cylinder gap).

Question 62

What kind of shape soot may a cylinder gap produce?

Answer 62

May produce a L-shaped or V-shaped grey sooty deposit on the skin or clothing.

Question 63

When powder escapes the cylinder gap what occurs?

Answer 63

Powder escaping from the cylinder gap may also result in tattooing of the skin. This tattooing however may be relatively sparse.

Question 64

What can happen is the barrel and the cylinder is out of line?

Answer 64

If the barrel and cylinder is out of line, fragments of the bullet may be sheared off are the bullet jumps from the cylinder to the barrel. These fragments can produce marks on the on the skin that resemble tattooing.

Question 65

What are flash suppressors?

Answer 65

Flash suppressors are attached to the muzzle of firearms and are are used to reduce the muzzle flash that can be seen when a firearm is discharged, especially at night.

Question 66

How is muzzle flash determined?

Answer 66

Muzzle flash is determined by the type of propellant, barrel length and muzzle pressure among other factors.

Question 67

What type of contact wound does the muzzle of a flash suppressor make?

Answer 67

If the muzzle of the weapon is held in contact with the body at the time of discharge, the flash suppressor will produce a distinctive pattern of seared, blackened areas around the entrance wound. When fully formed it results in a flower-like pattern of soot and seared skin.

Question 68

What are microtears?

Answer 68

Wounds from high-velocity centrefire rifle bullets may show small splits or tears radiating outward from the edges of a entrance wound. They may involve only a partial circumference of the entrance wound and are barely visible with the naked eye.

Question 69

What projectile can produce a mircotear?

Answer 69

These micro tears, though rarely, may also be seen from partial metal-jacketed high velocity pistol bullets.

Question 70

How does an Intermediary Targets affect the appearance of a wound?

Answer 70

The appearance of a wound may be altered as a result of the bullet passing through an intermediary target before striking a victim. This normally results in an alteration to the appearance of the wound or wounds.

Question 71

When passing through an intermediary object what may propel off the projectile and how does this affect wounds?

Answer 71

In passing through an intermediary object a bullet may propel fragments of the object forward with the bullet. This may result in fragments from the object being embeded in the skin as well as produce pseudopowder tattoo marks on the skin.

Question 72

What is a keyhole entrance wound?

Answer 72

A bullet striking the skull at a shallow angle may produce a keyhole wound of the bone.

Question 73

How is a keyhole shaped wound made?

Answer 73

The stress created when the bullet comes into contact with the bone, part of the bullet shears off and travels a short distance beneath the the scalp while the bulk of the bullet enters the cranial cavity. This results in a keyhole-shaped wound in the bone.

Question 74

What is back spatter?

Answer 74

Back spatter is the ejection of blood and tissue from a gunshot wound entrance. The occurrence and degree of back spatter depends on the location of the wound, the range and calibre of the weapon.

Question 75

What is back spatter in contact wounds?

Answer 75

back spatter refers to blood that is ejected rearwards towards the line of fire.

Question 76

What information can be received from back spatter on the hands?

Answer 76

It can be presumptive evidence that someone has fired a gun. This is especially so when it is found on the firing hand. While its presence may indicate that the person fired the gun, absence of back spatter does not mean they did not.

Question 77

Where on the firearm should be checked for blood or tissue?

Answer 77

It is most often detected on the outside of the muzzle than inside of the barrel.

Question 78

What does blood inside the barrel suggest?

Answer 78

The weapon was within a few inches of the body at the time of discharge.

Question 79

How can you determine the calibre of the bullet?

Answer 79

The calibre of a bullet cannot be determined by the diameter of the entrance wound. The size of the hole is due to the elasticity of the skin and the location of the wound, and not just the diameter of the bullet.