Gunshot wounds, Shotgun wounds

*Soot vs gunpowder

*Soot*- Lighter, won't tavel beyond 12in, doesn't get embedded in skin, removed by hot water or hydrogen peroxide *Gunpowder*- can travel up to 3ft, can get embedded in skin,

The severity of a gunshot wound is determined by the size of the __________ which depends on the amount of ______ lost in tissue

*Temporary cavity* which depends on the amount of *kinetic energy* lost in tissue

*Entrance wounds: Distant range wounds may be what shape?

*stellate/star shaped* especially over bony prominence of head Note: resembles exit wounds or contact wounds

**What is a Shored Exit Wound? What kind of abrasion does this create?

-Exit wound that results when skin is supported by a surface when the bullet exits (ie; a wall/ground). This creates a broad area of abrasion Ex) on ground & suspect shoots standing over victim. Bullet slaps skin against the ground

What are Reentrance Wounds? How do they look?

-Gunshot wound where the bullet passes through one body part and reenters elsewhere. -Typically has large irregular wound with an irregular abrasion ring. - Often has contusions/bruise and large rings of abrasions due to inc. in yaw

Shored Entrance Wound

-Gunshot wound where the entrance is supported by another portion of the body. -Often seen in reentrance wounds involving arm & chest. ex) A gun shot through the arm into the chest. The chest is supported by the arm being in contact with it

What are the 6 types of contact GSWs?

-Hard contact -Loose contact -Angled contact -Incomplete contact -Near contact -Near contact angled wounds

Exit Wound Characteristics (4)

-More variable -Rarely have surrounding abrasions since its pushing skin outward -Tissue isn't lost, so margin can be reapproximated - Heal better and are easier to suture

Near Contact Angeled Wounds

-Soot radiates outward from muzzle -Bulk of the zone is on the same side as muzzle -Opposite of pattern in angled contact wounds

Entrance wounds Characteristics (4)

-Usually round, oval, elliptical -Ring of abrasion around it -May have microtears if a high velocity rifle is used -Margins can not be reapproximated.

Bone perforation depends on (5)

-Velocity of bullet , -Bullet construction, -Wt of bullet, -Angle of interaction between bullet and bone, -Type of bone

Contact SGW of trunk

-less deformation because gases can expand in abdomen & chest (less than in head) -less gp & soot because barrel is longer

Contact SGW of head

-shreds brain, pressure waves increase severity of wounds & ejects brain tissue -Gas causes head to expand

distinguish suicidal and homicidal intraoral gsw

-suicidal intraoral gsw- proceed in backward, upwards trajectory bullet will come out of top of head -homicidal intraoral gsw more likely to be horizontal in its trajectory, so the bullet will come out of the back of the head

----SHOTGUN WOUNDS -------

...

Size & density of stippling pattern depends on ...(2)

1) Gunpowder type 2) Barrel length

Gauge (4)

1) describes the caliber of the shotgun 2) equals the number of lead balls of the bore diameter that makes up a lb**** 3)12 gauge: 12 Pb balls to make one lb 4) the larger the gauge the smaller the bore diameter

SGW: Describe wounds when Range of fire is 4 ft, 6-7ft & 10ft

4ft: main entrance surrounded by satellite wounds as pellets begin to disperse 6-7ft: cuff of satellite wounds 10ft: great variation depending on ammo, choke and range. multiple pellet holes

Billiard ball effect Can you determine range of fire?

As shotgun pellets enter the body, they hit each other and disperse. So you cannot determine range of fire in shotgun injury

*Yaw

Bullet instability as it enters a body. The rotation of the nose of the bullet away from the line of flight.

What are Ricochet Bullets? What characteristic is indicative of a ricochet bullet?

Bullets that produce larger, more irregular wounds due to tumble in air (inc. yaw). (change in trajectory of bullet; ex) bounces off something) -Characteristic: One surface of the bullet will be flattened*. May penetrate, but does not perforate body.

GP stippling depends on (3)

Caliber, Individual weapon, Intermediary objects

Modified Greiss Test

Checks for gp. Chemical test used on clothing to detect nitrites (orange). Used to determine range of fire.

Sodium Rhodizonate Test how does it differ from Greiss test? Can is tell you range of fire?

Chemical test used to detect lead residues around entrance defect (pink). Most lead arises from primer. Must be done after the Greiss test. Tells you if defect on clothing is bullet defect or not. *It's not used to determine exact range **

*Bullet wipe does not indicate _______ but may determine _______ & ____

Does NOT determine range of fire but may determine entrance from exit & sequence of fire

Gunpowder can travel ____ than soot

Farther (3 ft)

Lead snowstorm

Fragments of lead will break off core of bullet in body and produce "lead snowstorm" on X-ray. Due to high velocity center fire bullets usually found in long guns

Bullet wipe what is it? what is it made by? (2) what is it composed of ? (3)

Gray-black rim around an entrance *hole* (not wound) made by lead and full jacketed bullet. Not seen on the body. But can be seen on light colored clothing -Composed of soot, lubricant, and metallic elements. Does not indicate range of fire

How does Uncoated gunpowder look?

Green/beige powder grains

Hard Contact Gunshot Wound

Gunshot Wound where the gun is placed firmly against skin. The edges of the wound are seared by hot gas and blackened by soot. Gunpowder/soot are found within the wound tract. Tissue may have cherry red color from carboxyhemoglobin. Rarely accidental. Wound may be stellate or cruciform. Muzzle imprint usually present

What is a Tangential Wound? How can you determine where bullet came from ?

Gunshot wound into subcutaneous (innermost) tissue, with an area of abrasion at the entrance and torn margins of skin where the bullet moved. -The apices of the triangular, torn margins of skin, point toward direction of bullet entrance

Incomplete Contact gunshot wounds

Gunshot wound that occurs when a body surface is not flat (usually head). Muzzle is in contact with portion of the head. Characterized by elongated area of searing, gp & soot on the opp. side of the muzzle. (eccentrically distributed)

Keyhole Wounds

Gunshot wound where bullets striking at a shallow angle produce a wound with one edge having characteristics of an entrance wound, whereas the other edge has characteristics of beveling of an exit wound -fragment of bone may enter brain and become lethal

Skull Gunshot wounds: Contact wounds

Gunshot wound where gases enter the cranium and expand

Close/Intermediate range Gunshot Wounds

Gunshot wound where the muzzle is close enough for gunpowder stippling and/or soot deposition.

Near Contact Gunshot Wound

Gunshot wound where the muzzle is close to skin but not in contact. Too close for individual gunpowder stipple to be seen.-You'll see tight band of gp and soot around entrance wound. (It's a gray area between loose contact and near contact)

Distant Range Gunshot Wounds

Gunshot wound where the muzzle is far enough so that no soot/gunpowder is deposited on the body. (Muzzle is more than 3ft away ). Generally, no gunpowder will be travel beyond 3ft. At 4ft or 400 ft, entrance wound may look the same.

Loose Contact Gunshot wound

Gunshot wound where the muzzle is in light contact with skin. Soot and gunpowder deposited in a ring like/band around the wound. Muzzle imprint is not usually present.

Angled Contact Gunshot Wound

Gunshot wound where the muzzle is not in complete contact w/ skin but very close. Gas and soot will produce eccentric pattern. Entrance wound is at base of eccentric pattern.

Graze wound

Gunshot wound with elongated area of abrasion. Occurs on superficial layers of skin. Difficult to determine direction.

What causes secondary fractures in a gunshot wound to the skull?What is it dependent on? (2)

Intercranial pressure waves. Depends on range of fire and kinetic energy possessed by the bullet

how would a hard contact wound on abdomen look?

Less likely to see stellate defect because when wound isn't underlying bone, there is more room 4 gasses can expel

*Contact shotgun wounds show ____ stippling than handgun injuries. why?

Less; because barrel of shotgun is so long

when a revolver is used where can GP and soot be produced from? (2)

Muzzle & cylidner gap

Close/Intermediate range of fire

Muzzle of weapon is close enough (no skin contact) to the person to deposit gunpowder on the victim (stippling)

Does Shape and size of wound correlate with type of bullet? If not, what does size & shape depend on?

No, because skin is elastic However, size & shape of wound depend on location of exit wound: lax skin vs tight areas

How can you tell the difference between old bullet & new bullets retained in body?

Old bullets are surround by scar tissue, don't have hemorrhage around & they often become oxidized in body

Fractures to the skull are most common where? What can it produce?

Orbital plates because it's very thin -can produce "raccoon eyes"/spectacle hematoma

What should you store clothes in for evidence?

Paper bags

Pseudo-gunpowder stipple

Punctate abrasions of skin produced by objects other than gunpowder (ie; post mortem insect activity, petechiae, fragmented bullets, glass, etc). Usually larger and more irregular than regular stippling. Note: there can be pseudo GP soot as well

What is Range of Fire? what are the 3 types?

Range of fire- how far the muzzle of the weapon is to the person/or their clothing. 1) Contact 2) Close/Intermediate range 3) Distant Range

Distant range SGW: Entrance wound increases in size with distance. By 3 feet of you see ______ margins on wound. why?

Scalloped This is because pellets are starting to separate from main pellet mass. This may help determine range of fire.

How does Coated gunpowder look?

Shiny black powder grains

The only exit wounds that have abrasions are

Shored Exit wounds

When a bullet hits lax/loose skin (ex: neck, armpit) the exit site will look _____

Slit-like

Longer gun barrel produces _______area of soot

Smaller/Denser

When a bullet exits out of tightly-stretched skin (ex: head), the exit site will look _____

Stellate

What is Energy-dispersive x-ray? What for elements does it analyze for? Can it tell you range of fire?

Technique used to analyze for *copper*, *antimony*, *barium*, and *lead* on clothing. Gives approximation of range.

What can happen when Low velocity bullets may strike the skull?

They strike the skull, flatten and travel between the scalp and skull

Bullet Emboli what kind of bullets usually cause this?

Usually seen in small caliber, low-velocity bullets that are trapped in blood vessels (usually aorta/heart) and travel to the legs, pelvis, brain, etc. May be regurgitated/aspirated.

*What is Soot? Soot will not travel beyond how many inches?

Vaporized carbon that contains metal from primer, bullet, and cartridge case. *Will not travel beyond 12 inches.* Very light, so it *can be wiped away* or removed by hot water/hydrogen peroxide.

Intermediary Targets

When a bullet passes through an object before striking a person. The object may fragment & strike the person producing various injuries. This increases yaw to create an atypical entrance wounds.

Cylinder Gap

When cloth is wrapped around a revolver and fired. Can see L or V shaped blackened area on cloth. If there is no gap, it often means a semi-automatic handgun was used.

When do you see stellate appearance in hard contact wound?

When its tissue overlying bone

Gunpowder Stippling

When unburned gunpowder grains exits the gun causing pinpoint abrasions on the skin surrounding entrance wound. Can happen when muzzle is in close range w/ person. It *cannot be wiped away*. Generally does not occur beyond 3ft.

Penetrating gunshot wound

Wound where the projectile is still in the body. Has an entrance site, no exit site.

Perforating gunshot wound

Wound where the projectile leaves the body. Has an entrance and exit site.

Bullets striking at shallow angle may cause

a portion of bone to penetrate the brain & keyhole wound

why is it important to distinguish entrance vs exit wouns

b/c you want to recreate what happened. exit wounds are more variable than entrance wounds in size, shape, and configuration due to bullet tumbling breakup fragment as it goes through the body czing diff exit wounds or change in shape

how does GP/soot appear on light background?

black and gray

W/ GSW in bone how can you determine order of fire?

by looking at fracture lines, b/c fx lines won't cross. 1st bullets are parallel. 2nd are perpendicular

Cherry red discoloration found on skin near wound may be produced due to ...

carbon monoxide -component of gasses discharged from gun

*Filler is only found in ____ range Shotgun wounds

close range -Wad, fillers can't travel too far Note: looks like white fragments

differentiate the core and the jacket of the bullet

core has greater mass and velocity. core may be left behind and the core may leave the jacket behind and exit

Entrance wound: Variation in abrasion ring depends on...

direction that the bullet entered: concentric vs eccentric abrasion ring Note: Inc in yaw may cause eccentric abrasion

Exit wounds of bone will show ______

external beveling -hole on inner table of skull is smaller than hole on outer table

What can bone fragments form after being struck by bullet and what makes them so bad

form secondary projectiles as the bullet strikes bone, this can be more lethal than the bullet itself. bone can exit the body

Skull Gunshot wounds: Distant range wounds

fractures produced by pressure from the temporary cavity formation

what's essential to identify intraoral gsw (2)

hard palate & tongue

Entrance wounds of bone will show ______

internal beveling hole on outer table of skull is smaller than whole on inner table

What's the most impt portion of the bullet and should be collected?

jacketed portion b/c it can have lands and grooves from the firearm

how does gp/soot appear on black background?

looks grayish white

Can you see abrasion rings on entrance wounds of palms & soles?

no you may not see abrasion ring there because of the nature of epidermis.

In contact shot gun wounds, gunpowder may be found on the _______ of the shooter

non dominant hand

SGW: wad/cup injury produce what type of marks?

petal marks

What can scalloping help determine?

range of fire

Is it likely that people will develop PB poisoning from retained bullets

rare, only occurs if lead bullet is in synovial joint, bone, or vertebral disc. -can cz intranuclear inclusions in hepatocytes -many retained bullets don't do any harm and are left as trophy bullets

shotgun shell includes (5)

shot, cup, wad, gunpowder, primer

Shotgun ______ are single projectiles that may be encased in a _______

slugs; sabot (plastic covering over slug). They may cause adjacent injuries.

When muzzle is in contact with the skull , it often produces what shape wound ?

stellate, star wound because gas is expanding outward

Gutter wounds of skull

tangential wounds; has 3 degrees

What can you see in an intraoral shotgun injury?

tears around corner of the mouth