Gunshot wounds
are either penetrating or perforating. Penetrating wounds occur when a bullet enters an object and does not exit;
in perforating wounds, the bullet passes completely through the object. A wound,
however, can be both penetrating and perforating. Gunshot wounds can be
divided into four broad categories, depending on the range from the muzzle to target: contact, near
contact, intermediate, and distant. In contact wounds, the muzzle of the weapon
is held against the surface of the body at the time of discharge. Contact wounds may be
hard, loose, angled, or incomplete. In
hard-contact wounds, the muzzle of the weapon is jammed “hard” against the
skin, indenting it, so that the skin envelops the muzzle. In hard contact
wounds, the immediate edges of the entrance are seared by the hot gases of
combustion and blackened by the soot. This soot is embedded in the seared skin
and cannot be completely removed either by washing or by vigorous scrubbing of
the wound. In loose-contact wounds, the muzzle, while in complete contact with
the skin, is held lightly against it. Gas preceding the bullet, as well as the
bullet itself, indents the skin, creating a temporary gap between the skin and
the muzzle through which gas can escape. Soot carried by the gas is deposited
in a zone around the entrance. This soot can be easily wiped away. A few
unburnt grains of powder may also escape out this gap and be deposited on the
skin in the zone of soot. In angled-contact wounds, the
barrel is held at an acute angle to the skin so that the complete circumference
of the muzzle is not in contact with it. Gas and soot escaping from the gap,
where contact is not complete, radiate outward from the muzzle, producing an
eccentrically arranged pattern of soot. The soot is arranged in two different
zones. The most noticeable zone, and often the only one seen, is a blackened
seared area of skin or cloth having a pear, circular, or oval configuration. On
the skin, this light zone is usually washed away, obscured by bleeding or
removed in cleaning the wound for examination. A few unburnt grains of powder
may be deposited in these zones. As the angle between the barrel and the skin increases,
i.e., the barrel moves toward a perpendicular position to the skin, the
entrance hole will be found more toward the center of the zone. If the angle
between the barrel and the skin decreases, the gap between the muzzle and skin
becomes larger, and more material can escape through the gap. At some point,
the gap becomes sufficiently large that unburnt grains of powder escaping
through the gap will skim over the zone of seared skin, fanning out from the
entrance, impacting distal to the entrance wound in a fan shaped pattern of
powder tattooing. Incomplete-contact wounds are a variation of angled-contact
wounds. In these, the muzzle of the weapon is held against the skin, but,
because the body surface is not completely flat, there is a gap between the
muzzle and the skin. A jet of soot-laden gas escapes from this gap producing an
area of seared, blackened skin. The location of this seared, blackened zone can
be anywhere in relationship to the muzzle circumference, depending on where the
gap is. The most probable cause for the appearance of this wound is a momentary
break in contact between the muzzle and skin along the lower margin of the
barrel as the victim reaches for the trigger with one hand while holding the
muzzle against the skin with the other hand. In all contact wounds, soot, powder,
carbon monoxide, and vaporized metals from the bullet, primer, and cartridge
case are deposited in and along the wound tract. Near-contact wounds lie in a gray zone between contact
and intermediate range wounds. In near contact wounds, the muzzle of the weapon
is not in contact with the skin, being held a short distance away. The
distance, however, is so small that the powder grains emerging from the muzzle
do not have a chance to disperse and mark the skin, producing the powder tattooing
that is the sine qua non of intermediate-range wounds. The soot in the seared zone is baked into the skin and
cannot be completely wiped away. Small clumps of unburned powder may be present
in the seared zones.The location of the blackened seared zone to the entrance
hole is different from that seen in angled contact wounds, however. In
near-contact angled wounds, the bulk of the blackened, seared zone is on the
same side as the muzzle, i.e., pointing toward the weapon. This is the opposite
of what is found in angled contact wounds. In contact wounds, however, this area lies on the side
opposite to the muzzle, pointing the direction in which the bullet was fired.
In near-contact wounds, the seared and blackened area lies on the same side as
the muzzle of the weapon. Things are never as simple as one
might wish, however. Thus, in angled contact wounds, the entrance wound should
be present at the base of the seared, blackened zone. By increasing the angle
between the barrel and the skin, however, this entrance will move toward the
center of the zone. This same picture can also be produced by a near-contact
angled wound if the distance from muzzle to target is approximately 5 mm. For
that reason one cannot always differentiate between a contact and a near
contact angled wound. An intermediate-range gunshot wound
is one in which the muzzle of the weapon is held away from the body at the time
of discharge yet is sufficiently close so that powder grains expelled from the
muzzle along with the bullet produce “powder tattooing” of the skin. The powder grains emerging from the muzzle may be
deposited in the seared zone around near-contact wounds though individual
tattoo marks are not seen. As soon as one sees individual tattoo marks, one is
dealing with an intermediate-range wound. For handguns, powder tattooing begins
at a muzzle-to-target distance of approximately 10 mm. Tattooing consists of numerous reddish-brown to
orange-red punctate lesions surrounding the wound of entrance. When the muzzle
of the weapon is at an angle to the skin, the skin under the muzzle, i.e., on
the same side as the barrel, will show denser tattooing than the skin on the
other side of the entrance hole. Powder
tattooing is an antemortem phenomenon and indicates that the individual was
alive at the time they were shot. If the individual was dead before being shot,
although the powder may produce marks on the skin, these marks have a moist
gray or yellow appearance rather than the reddish-brown to orange-red
coloration of an antemortem wound. There should be no difficulty with differentiating
the two. The term “powder burns” should never be used because one does not know
to what phenomenon the term is being applied. Some individuals use the term
“powder burns” to signify powder tattooing, whereas others use it to signify
searing and blackening of the skin due to the hot gases that occur from
combustion of the propellant. Black powder grains could also penetrate into the
dermis and produce literal tattooing. The burning grains of black powder were
capable of setting clothing on fire, a characteristic not possessed by
smokeless powder. In other words “powder tattooing” is just one form of
stippling with the term “powder tattooing” used to refer to stippling unquestionably
and exclusively due to powder grains. If the marks are due to material other
than powder or if one is not certain of their origin, then, one uses the term
“stippling.” It is probable that the thickness of the stratum corneum in this
area protects the dermis from any trauma — direct or indirect — arising from
the impact of powder grains; thus there is no dermal vital reaction and,
therefore, no true tattooing.
When a weapon is discharged, in addition to powder,
soot produced by combustion of the gunpowder emerges from the muzzle of the
weapon. The size, intensity, and appearance of the soot pattern and the maximum
range out to which it occurs depend on a number of factors:
1. Range
2. Propellant
3. Angle of the muzzle to the target
4. Barrel length
5. Caliber of the weapon
6. Type of weapon
7. Target material and the state of the target (bloody or
non-bloody)
The propellant is a determinant as to the amount of
powder soot present in that some powders burn more cleanly than others. Thus,
in a test using a .22-caliber revolver with a 6-in. barrel, two forms of .22
Long Rifle ammunition were fired at white cotton cloth. One form of ammunition
was loaded with flake powder; the other with ball powder. Not uncommonly, a
gunshot wound is covered with blood — wet, dried, or caked. In the process of
cleaning the blood off the wound, soot may be wiped off. There are two methods
of removing the blood without removing the soot. The first and simplest is to
direct a spray of hot water at the wound. After a time, the water will wash
away the blood but leave the soot. Blood can also be removed by pouring
hydrogen peroxide on it. This will dissolve the blood, breaking up any clots. In
addition to the pattern produced by soot emerging from the muzzle, a soot
pattern can be produced by soot escaping from the cylinder-barrel gap. If a gun
is held at an acute angle to the body, there will be a deposit of soot,
possibly associated with a zone of searing, from the cylinder gap as well as
searing and soot at the entrance from gas emerging from the muzzle. In addition
to the soot, powder escaping from the cylinder gap may produce tattooing of the
skin. This tattooing will be relatively sparse. If the cylinder of the revolver
is out of alignment with the barrel, as the bullet jumps from the cylinder to
the barrel, fragments of metal may be sheared off the bullet. A silencer is a device for diminishing the sound of a
discharging firearm. No silencer is completely effective and some individuals
prefer the term “sound suppressor” for these devices. The noise created on
firing a weapon originates from the fall of the hammer or firing pin;
detonation of the primer; the wave of gas and air exiting the barrel before the
bullet; the bullet exiting; the propellant gas wave and the operation of the
gun mechanism as the fired case is extracted and ejected and a new round chambered.
This last noise may be deleted by locking closed the action of the weapon so
that ejection and chambering of a new round is done manually. Silencers may be either an integral part of a weapon
or attached to the muzzle. Most silencers are cylindrical devices attached to
the muzzle of a gun. The cylinder is typically filled with metal or rubber
baffles (disks) with a central hole through which the bullet can pass. In crude
silencers, the cylinder may be stuffed with steel wool or fiberglass. This last solution is accomplished by drilling
multiple holes down the barrel so as to bleed off some of the propellant gas
causing the bullet to be traveling at subsonic velocity when it exits. Silencers are rarely encountered. More common are
muzzle-brakes and compensators. Just as in a silencer, they may be integral
with the barrel or attached to the muzzle. A muzzle brake
works by re-directing some of the gases at the muzzle so as to generate a
forward thrust on the muzzle countering the force of recoil, i.e., reducing
recoil. A compensator diverts gas upward to counteract the tendency for the
muzzle to rise on firing. The terms muzzle brake and compensator are often used
interchangeably. In distant wounds, the only marks on the target are those
produced by the mechanical action of the bullet in perforating the skin. Most
entrance wounds, no matter the range, are surrounded by a reddish, reddish-brown
zone of abraded skin — the abrasion ring. Fresh entrance wounds have an abrasion ring with a
moist, fleshy appearance. As the abrasion ring dries out, however, it assumes
the more familiar appearance. The abrasion ring is also not due
to the bullet burning the skin. While bullets may easily attain a surface
temperature of over 100°C after leaving the muzzle, the contact time between
the bullet and skin is extremely short. The
abrasion ring can vary in width, depending on the caliber of the weapon, the
angle at which the bullet entered, and the anatomic site of entrance. Entrance
wounds in the skin overlying the clavicle generally have a wider abrasion ring
than those in other parts of the body, possibly due to reinforcement of a thin
layer of skin by curved bone. The bullet may be fired perpendicular to the body
but strike a projecting surface, e.g., the breast so that an eccentric abrasion
ring wound is produced even though the bullet is going straight into the body.
Thus, it is never possible to say with certainty in which direction a bullet
has traveled through the body from examination of the entrance wound alone. Occasionally
an entrance wound will not have an abrasion ring observable either by naked eye
or by dissecting microscope. This can be due to the nature of the bullet or the
location of the entrance wound. Distant or intermediate entrance wounds of the
palms and soles differ from wounds of the skin in other areas of the body in
that the entrance is stellate, with tears 1 to 3 mm in length radiating from
the entrance perforation; or are “H” shaped or slit-like. Distant gunshot
wounds of the head may have a stellate or irregular appearance simulating a
contact wound. This phenomena is seen with both handgun and rifle bullets. It
is most common over bony prominence such as the orbital ridges. In
intermediate-range wounds, microscopic sections of the entrance should show
grains of powder embedded in the skin adjacent to the entrance hole. Although
true ball powder quite commonly embeds itself in the skin, flake powder
generally bounces off. For the most part, the grains of powder are embedded in
the epidermis. Ball powder, and on occasion flake powder, may however,
perforate the epidermis, coming to rest in the upper dermis. In gunshot wounds, the dermis underneath the abrasion
ring and adjacent to the wound track shows alterations in the appearance of the
collagen. These alterations have been ascribed to the thermal effects of hot
gases in close range wounds and the thermal effects of a “hot bullet” in
distant wounds. Exit wounds are typically larger and more irregular than entrance
wounds and, with rare exception, do not possess an abrasion ring. Exit wounds
can be stellate, slit-like, crescent, circular, or completely irregular. as the
missile travels through the body, its natural yaw is accentuated; if it travels
through enough tissue it will eventually tumble ending up traveling base first.
Second, the bullet may be deformed in its passage through the body. Both
factors result in the presentation of a larger area of bullet at the site of
exit, with resultant larger and more irregular exit wounds. Shored exit wounds are characterized by a broad, irregular
band of abrasion of the skin around the exit. In such wounds the skin is
reinforced, or “shored,” by a firm surface at the instant the bullet exits. Occasionally,
a bullet traveling through the body will lose so much velocity that, while it
may have sufficient velocity to create an exit hole, the bullet will not exit.
This may be due to the elastic nature of the skin or resistance to its exiting
by either an overlying garment or an object such as a seat back or wall. In the
latter case, the “exit” may show shoring of its edges. Although exit wounds are typically larger than
entrance wounds, it is possible for an exit to be smaller than the entrance and
in fact smaller in diameter than the bullet. The last phenomenon is due to the
elastic nature of the skin. A common and seemingly logical
assumption that is not usually true is that a bullet on exiting the body will
continue in a straight path that is a continuation (projection) of the path the
bullet followed in the body. As a bullet passes through the body, however, it
becomes unstable and its yaw increases. If the path is sufficiently long, the
bullet will tumble, ending up traveling base forward. The farther such a bullet
moves from the exit, the more the bullet will veer from its projected
trajectory. If in passing through the body the bullet undergoes deformation,
this will also contribute to the tendency of the bullet to veer off its
projected course. A graze wound is one in which a bullet strikes the skin at a
shallow angle, producing an elongated area of abrasion without actual
perforation or tearing of the skin. In a tangential wound, the injury extends
down through to the subcutaneous tissue. The skin is torn, or “lacerated,” by
the bullet. Superficial perforating wounds are shallow through-and-through wounds
in which the entrance and exit are close together. They may be difficult to
interpret. The entrance will usually have a complete but eccentric abrasion
ring, whereas the exit will have abrasion of only a portion of the circumference.
The abrasion at the exit points the way the bullet was moving; the eccentric abrasion of the entrance, the
way the bullet was coming from. Re-entry wounds occur when a
bullet has passed through one part of the body and then reentered another part.
The portion of the body initially perforated serves as an intermediary target.
Most commonly, this occurs when a bullet perforates an arm and enters the
thorax. Shoring of an entrance wound may be seen with a re-entry wound of the
chest from a bullet that perforated the arm. This occurs when the arm is
against the chest at the time the bullet perforated the arm and entered the chest.
The chest “shores up” the exit in the arm and the arm “shores up” the entrance
in the chest. The gyroscopic spin that stabilizes a bullet as it travels
through the air is insufficient to stabilize the bullet as it passes through a
solid object. Because of this, the bullet’s yaw is accentuated and the bullet
may wobble violently. In addition, the bullet may be deformed in its passage
through the object. As a result of these factors, when the bullet does strike
the victim, the entry wound is usually atypical. A bullet ricocheting off a
hard surface can generate secondary fragments that may produce stippling of the
skin. These marks can be due to fragments of wood or stone from the surface
from which the bullet ricocheted or to metal fragments from the bullet itself. On firing the weapon, fragments of the steel wool may
be propelled out the end of the silencer, embedding themselves in the skin
around the entrance. These markings are relatively sparse and fragments of the
steel wool often can be found embedded in the skin. Occasionally, a lead bullet recovered from a body is
flattened on one surface like a ricocheted bullet, even though the bullet could
not have ricocheted. This occurs when the bullet, on entering the body, strikes
a heavy bone such as the femur, flattening on the bone. Tangential wounds of
the skull have classically been called “gutter wounds.” In first-degree gutter wounds only the outer table of
the skull is grooved by the bullet, with resultant carrying away of small bone
fragments. Fragments of bone can be driven
into the brain causing death. After third-degree wounds come “superficial
perforating wounds.” Here there is production of separate entrance and exit
wounds in the bone. A bullet striking the skull at a
shallow angle may produce a punched out oval defect in the skull without the
bullet actually entering the cranial cavity. The bullet may flatten out and
either be recovered from beneath the scalp or exit. The fragments of bone may
be driven into the brain and cause death. A bullet striking the skull at a shallow angle may
produce a keyhole wound of the bone. The size of the hole is due not only to
the diameter of the bullet but also to the elasticity of the skin and the
location of the wound. An entrance wound in an area where the skin is tightly
stretched will have a diameter different from that of a wound in an area where
the skin is lax. Bullet wounds in areas where the skin lies in folds or creases
may be slit-shaped.
Acknowledgements:
The Police Department;
www.politie.nl and a Chief Inspector – Mr. Erik
Akerboom ©
Bibliography:
1. Criminal
Investigations – Crime Scene Investigation.2000
2. Forensic
Science.2006
3. Techniques
of Crime Scene Investigation.2012
4. Forensics
Pathology.2001
5. Pathology.2005
6. Forensic
DNA Technology (Lewis Publishers,New York, 1991).
7. The
Examination and Typing of Bloodstains in the Crime Laboratory (U.S. Department
of Justice, Washington, D.C., 1971).
8. „A
Short History of the Polymerase Chain Reaction". PCR Protocols. Methods in
Molecular Biology.
9. Molecular
Cloning: A Laboratory Manual (3rd ed.). Cold Spring Harbor,N.Y.: Cold Spring
Harbor Laboratory Press.2001
10. "Antibodies
as Thermolabile Switches: High Temperature Triggering for the Polymerase Chain
Reaction". Bio/Technology.1994
11. Forensic
Science Handbook, vol. III (Regents/Prentice Hall, Englewood Cliffs, NJ, 1993).
12. "Thermostable
DNA Polymerases for a Wide Spectrum of Applications: Comparison of a Robust
Hybrid TopoTaq to other enzymes". In Kieleczawa J. DNA Sequencing II:
Optimizing Preparation and Cleanup. Jones and Bartlett. 2006
13. Nielsen
B, et al., Acute and adaptive responses in humans to exercise in a warm, humid
environment, Eur J Physiol 1997
14. Molnar
GW, Survival of hypothermia by men immersed in the ocean. JAMA 1946
15. Paton
BC, Accidental hypothermia. Pharmacol Ther 1983
16. Simpson
K, Exposure to cold-starvation and neglect, in Simpson K (Ed): Modem Trends in
Forensic Medicine. St Louis, MO, Mosby Co, 1953.
17. Fitzgerald
FT, Hypoglycemia and accidental hypothermia in an alcoholic population. West J Med
1980
18. Stoner
HB et al., Metabolic aspects of hypothermia in the elderly. Clin Sci 1980
19.
MacGregor DC et al., The effects of ether, ethanol, propanol and butanol on
tolerance to deep hypothermia. Dis Chest 1966
20. Cooper
KE, Hunter AR, and Keatinge WR, Accidental hypothermia. Int Anesthesia Clin
1964
21. Keatinge
WR. The effects of subcutaneous fat and of previous exposure to cold on the
body temperature, peripheral blood flow and metabolic rate of men in cold
water. J Physiol 1960
22. Sloan
REG and Keatinge WR, Cooling rates of young people swimming in cold water. J
Appl Physiol 1973
23. Keatinge
WR, Role of cold and immersion accidents. In Adam JM (Ed) Hypothermia – Ashore
and Afloat. 1981, Chapter 4, Aberdeen Univ. Press, GB.
24. Keatinge
WR and Evans M, The respiratory and cardiovascular responses to immersion in
cold and warm water. QJ Exp Physiol 1961
25. Keatinge
WR and Nadel JA, Immediate respiratory response to sudden cooling of the skin.
J Appl Physiol 1965
26. Golden
F. St C. and Hurvey GR, The “After Drop” and death after rescue from immersion
in cold water. In Adam JM (Ed). Hypothermia – Ashore and Afloat, Chapter 5,
Aberdeen Univ. Press, GB 1981.
27. Burton
AC and Bazett HC, Study of average temperature of tissue, of exchange of heat and
vasomotor responses in man by means of bath coloremeter. Am J Physiol 1936
28. Adam
JM, Cold Weather: Its characteristics, dangers and assessment, In Adam JM (Ed).
Hypothermia – Ashore and Afloat, Aberdeen Univ. Press, GB1981.
29. Modell
JH and Davis JH, Electrolyte changes in human drowning victims. Anesthesiology
1969
30. Bolte
RG, et al., The use of extracorporeal rewarming in a child submerged for 66
minutes. JAMA 1988
31. Ornato
JP, The resuscitation of near-drowning victims. JAMA 1986
32. Conn
AW and Barker CA: Fresh water drowning and near-drowning — An update.1984;
33. Reh
H, On the early postmortem course of “washerwoman’s skin at the fingertips.” Z
Rechtsmed 1984;
34. Gonzales
TA, Vance M, Helpern M, Legal Medicine and Toxicology. New York, Appleton-Century
Co, 1937.
35. Peabody
AJ, Diatoms and drowning – A review, Med Sci Law 1980
36. Foged
N, Diatoms and drowning — Once more.Forens Sci Int 1983
37. "Microscale
chaotic advection enables robust convective DNA replication.". Analytical
Chemistry. 2013
38. Sourcebook
in Forensic Serology, Immunology, and Biochemistry (U.S. Department of Justice,
National Institute of Justice, Washington, D.C.,1983).
39. C.
A. Villee et al., Biology (Saunders College Publishing, Philadelphia, 2nd
ed.,1989).
40. Molecular
Biology of the Gene (Benjamin/Cummings Publishing Company, Menlo Park, CA, 4th
ed., 1987).
41. Molecular
Evolutionary Genetics (Plenum Press, New York,1985).
42. Human
Physiology. An Integrate. 2016
43. Dumas
JL and Walker N, Bilateral scapular fractures secondary to electrical shock.
Arch. Orthopaed & Trauma Surg, 1992; 111(5)
44. Stueland
DT, et al., Bilateral humeral fractures from electrically induced muscular
spasm. J. of Emerg. Med. 1989
45.
Shaheen MA and Sabet NA, Bilateral simultaneous fracture of the femoral neck
following electrical shock. Injury. 1984
46.
Rajam KH, et al., Fracture of vertebral bodies caused by accidental electric
shock. J. Indian Med Assoc. 1976
47. Wright
RK, Broisz HG, and Shuman M, The investigation of electrical injuries and
deaths. Presented at the meeting of the American Academy of Forensic Science,
Reno, NV, February 2000.
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