Gunshot Wounds

Front 1

Statistics of gunshot wounds

Back 1

-2/3rds of all homicides in the US are caused by firearms
-Non-fatal injuries: 200,000 per year
-Deaths by firearms are the second leading cause of non-natural deaths in childhood and adolescence

Front 2

Two main reasons for death by firearms

Back 2

-Availability of weapons
-"Gun culture"

Front 3

Two general classes of firearms

Back 3

-Rifled weapons (handguns, rifles)
-Smooth bore shotguns

Front 4

Characteristics of rifled firearms

Back 4

-Fire one projectile at a time
-Gyroscopic effect, spin: stabilizes bullet in the air
-Individual characteristics: leave marks on the bullets that are used to identify the bullet

Front 5

Handguns

Back 5

-Low-velocity weapon
-Muzzle velocity 1400 ft/sec

Front 6

Rifles

Back 6

-High-velocity weapons
-Muzzle velocity for center fire weapon: 4000 ft/sec

Front 7

What really comes from the barrel of a gun?

Back 7

-Flaming gas that travels for a few inches and produces a burn
-Soot that travels for a few more inches (6-7" for most handguns) and produces a soot mark ("smudge")
-Unburned powder that travels for up to a few feet (3' usually for a handgun) and produces powder tattooing that will scrape the skin
-Bullet that enters or grazes the body

Front 8

Perforating firearm wound

Back 8

-Entrance and exit wound are both present
-Entrance wound is very round
-Exit wound is irregular and wider

Front 9

Penetrating firearm wound

Back 9

-Projectile(s) remain in the body
-No exit wound or near exit wound

Front 10

Entrance wounds provide two types of information

Back 10

-Range of fire
-Direction of fire

Front 11

Range of fire

Back 11

-To get a reliable estimate of the range, the particular gun and type of ammunition must be test-fired
-Entrance wounds are classified as:
Contact wounds
Near contact wounds
Medium/Intermediate range wounds
Distant wounds

Front 12

Contact wounds

Back 12

-Soot on adjacent skin
-Residues in proximal track
-Muzzle imprint
-Hard contact wound or loose contact wound

Front 13

Hard contact wound

Back 13

Muzzle pressed against the skin
-Burned edges
-Soot embedded in edges
-Soot and gunpowder in proximal track

Front 14

Loose contact wound

Back 14

-Temporary gap at discharge
-Soot on adjacent skin
-Circular pattern if gun perpendicular to skin
-Eccentric pattern if gun at an angle to the skin (broader area of soot on opposite side of muzzle)
-Soot and gunpowder in proximal track

Front 15

Near contact wounds

Back 15

-2 to 5 inches
-Muzzle a short distance from skin
-Central perforation with circular zone of soot
-Eccentric pattern if weapon at an angle (broader area of soot on same side as muzzle)

Front 16

Medium/intermediate range wounds

Back 16

-Presence of gunpowder tattooing adjacent to wound
-1-2 inches gunpowder particles centered around wound, with broader area of soot deposition
-6-7'' (15-18 cm), amount of soot decreases, abundant gunpowder present
-With increasing muzzle-target distance, zone of distribution of tattooing increases and density of particle dispersion decreases

Front 17

Distant wounds

Back 17

-2 to 4 feet for most handguns
-2 to 3 feet for center fire rifles
-No soot or gunpowder deposition

Front 18

Direction of fire

Back 18

-"Abrasion collar"
-Circular, of uniform width, if bullet strikes perpendicularly
-Eccentric if bullet strikes at an angle

Front 19

Exit wounds

Back 19

-Larger, more irregular than entrance wounds:
-No abrasion collar
-Stellate
-slit-like
-shored (may cause confusion with entrance wound)

Front 20

Atypical gunshot wounds

Back 20

-Graze wounds when bullet strikes at a shallow angle and abrades the surface of the skin
-More than one projectile
-Tangential wound
-Therapeutic intervention
-Wounds of palms and soles
-Wounds of the head
-Re-entry wounds

Front 21

Tangential wound

Back 21

-Bullet strikes at shallow angle
-Tears the skin, creating an elongated wound
-Tears along the margins point to the direction of the bullet

Front 22

Therapeutic intervention

Back 22

-Shape of the wound can be distorted
-Residues can be difficult to interpret

Front 23

Wounds of palms and soles

Back 23

-Usually stellate
-No abrasion collar

Front 24

Wounds of the head

Back 24

-Entrance wound often stellate
-Bevelling of cranial bone allow for differentiation between entrance/exit wound
-"Keyhole" gunshot wound

Front 25

Entrance? Exit? How was this person shot?

Back 25

-Entrance on the left because of the smooth edges
-Exit on the right with external bevelling
-"Keyhole" entrance
-Bullet grazed side of head

Front 26

Diagram to show difference between range of fire and entrance/exit wounds

Back 26

Front 27

Re-entry wounds

Back 27

No abrasion collar

Front 28

Entrance wounds from smooth-bore weapons/shotguns

Back 28

-Vary in size and shape depending upon the distance between the muzzle of the gun and the target:
-Round perforation
-Wound with scalloped margins
-Large wound with satellite small perforations
-Multiple small perforations

Front 29

Range of fire from smooth-bore weapons/shotguns

Back 29

Provided by:
-Presence or absence of residue
-Penetration or absence of penetration of wads
-Appearance of Entrance wound

Front 30

Contact wound from smooth-bore weapons/shotguns

Back 30

-Circular wound, the shot penetrates as a single mass
-Hard contact: muzzle imprint
-Loose contact: soot on adjacent skin.
-Soot and gunpowder in proximal track
-Wads and plastic cup in the wound

Front 31

Intermediate range wounds from smooth-bore weapons/shotguns

Back 31

-Powder tattoing on skin around entrance wound
-Tattoing can occur up to a distance of 30-40" (60-75 cm)
-"Cookie-cutter"appearance of wound edges, at 3 feet
-Satellite pellets holes around entrance at 4 feet
-Wads in wound track
-"Petal marks" from open plastic wad at 12-36" (30-90 cm)

Front 32

Distant wounds from smooth-bore weapons/shotguns

Back 32

- Number of individual pellet holes increases
-Size of main entrance decreases
-Wad does not penetrate but can strike body (5-8 ft, 150-240 cm)
-No wad imprint beyond 8 ft

Front 33

Determination of direction of fire from smooth-bore weapons/shotguns

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-Circular, symmetrical wound , if coming at right angle
-Elliptic wound if coming at an angle
-Shelving of edges, undercutting of margin opposite direction of shot

Front 34

Exit wounds from smooth-bore weapons/shotguns

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-Very large wounds in head, neck, small individuals
-Otherwise, uncommon

Front 35

Internal injuries caused by rifled ammunition

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-The more kinetic energy lost in the tissue, the greater the damage
-Tissue factor:
-Specific gravity and elasticity play a role
-The greater the specific gravity, the greater the damage

Front 36

Internal injuries caused by low-velocity weapons

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-Injury by crushing and punching
-Injury limited to tissue along track

Front 37

Internal injuries caused by high-velocity weapons

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-Large temporary cavity
-Outstretching of tissue behind bullet
-Injury at distance from bullet track

Front 38

Internal injuries caused by shotgun ammunition

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Damage is due to direct mechanical disruption

Front 39

Bullet wound deaths are caused by...

Back 39

-Hemorrhage, internal or external
-Cardiac or respiratory malfunction/arrest
-Brain dysfunction
-Infection
-Pulmonary Embolism