The pattern of injury seen at the entrance of a gunshot wound can provide some information as to the distance between the gun and the victim.
Entrance vs exit wounds
(1) Entrance wounds may be surrounded by a narrow zone of abrasion and discoloration produced by the bullet; the abrasion is produced as the skin is stretched over by the nose of the bullet, and this area tends to be larger than the residual hole made by the bullet.
(2) Exit wounds tend not to have an abrasion zone, but may show one if there is overlying support of the skin (belt, firm surface, tight clothing).
(3) Examination of clothing for residues can help distinguish entrance from exit wounds in difficult cases.
(4) Both entrance and exit wounds can show marginal lacerations.
(5) A linear tear suggests an exit wound.
(6) The number of wounds should be counted; the presence of an odd number may indicate that a bullet has not exited and is still in the victim.
Combustion particles:
(1) Completely combusted gunpowder results in a fine, dustlike black residue that travels only a few inches from the gun muzzle before it dissipates into the air; this is referred to as smudging and can be easily washed from the skin.
(2) Larger particles of partially burned or unburned powder and of metallic fragments create dotlike impressions referred to as stippling; the stippling usually cannot be washed away since the particles are driven into the skin (tattooing) and may cause minute hemorrhages.
(3) The greater the distance between the muzzle and the target, the greater the dispersion zone of the particulate residue.
(4) Test firings of the weapon with the suspected ammunition at varying distances from target can produce patterns of combustion particles which can be compared with the victim and the victim's clothing.
|
Wound Type |
Features |
|---|---|
|
contact (muzzle pressed against target) |
• blast effect of expanding gas and particles is within the target; skull wounds show crepitation of the tissue between scalp and skull due to the gases; abdominal wounds show cavitation due to the blast effect • the entrance wound may be smooth or show marginal lacerations; the latter cases may be confused with an exit wound • no pattern of particulate matter is seen surrounding the entrance wound • very little evidence of heat burn except for a sharply defined circular zone peripheral to the entry hole |
|
near contact |
• carbonaceous residue (burnt and unburnt powder) around the margins of the entry forms a ring • blast and gas effects inside the wound; clothing may show blast damage |
|
distance of 5-15 cm |
• heat effect due to hot gas, depending on the weapon and cartridge loading; this may result in light charring such as singed hair • a dark circle of smudging from the carbonaceous material surrounds the entry hole. • particulate matter is in a close well-defined zone around the entry wound |
|
distance of 15-30 cm |
• heat effects begin to disappear • smudging may be undetectable • discrete particles make their appearance in a circle of spread which increases with distance |
|
distance of 30-45 cm |
• particles remaining in the pattern change from small to large |
|
distance of 45 cm and further |
• target residue becomes scattered and at some point no residue is found except the dark ring which distinguishes the hole of entry from the exit wound (unless the target has fragmented on impact) |
|
Heat effect |
Smudging |
Particles |
Distance |
|---|---|---|---|
|
within and along the edge of the wound |
inside the wound |
inside the wound |
contact |
|
in wound; clothing may show blast damage |
tight ring around the rim of the wound |
tight ring |
near contact (< 5 cm) |
|
light charring or singed hair |
circle around wound |
circle around wound |
5 to 15 cm |
|
variable |
variable |
discrete |
15 to 30 cm |
|
absent |
absent |
large only |
30 to 45 cm |
|
absent |
absent |
none to few large |
> 45 cm |
Shotgun wounds:
(1) Wadding will penetrate the target or wound if at close range.
(2) Pellets spread in an ever-increasing diameter of pattern; at close ranges the pellets will cut a clean hole through the skin.
(3) The degree of choke in the gun can affect the pattern at a specific range.
Purpose: To estimate the distance between a gun and a victim based on the pattern seen at the entrance wound.
Specialty: Clinical Laboratory, Surgery, orthopedic, Emergency Medicine, Surgery, general
Objective: other testing, public health
ICD-10: T14.1, W32, W33, W34,
