Gunshot Wounds -

Certification of GSW

"Gunshot wound of (blank) with injuries of (blank)" - Manner is homicide or suicide. Rarely ever "accidental", only for hunting accidents

Fouling v. Stippling

- *Fouling*: Soot, residue of completely burned powder. > dust-like and wipes off. - *Stippling* (tattooing): Unburnt powder and debris, causing punctate impressions on target (does not wash off of skin). > Larger and heavier than soot so it travels farther. [Never use words POWDER BURNS].

Definitions

- *Penetrating*: Enters but does not exit. - *Perforating*: Enters and exits - *Track*: Detectable evidence that something has passed. Course along something has moved (Bullet path is a TRACK not a tract) - *Tract*: A system of bodily parts or organs that collectively serve some combined anatomic purpose. - *Magnum*: Cartridge which uses the same caliber and bullet but has more powder.

Extend of injury depends on:

- Bullet size (mass) - Velocity (V) - Bullet Shape (round, hollow point) - Spin - Jacket - Distance from muzzle to target - Nature of tissue

Shotgun Injuries

- Contact shotgun wounds of the head are devastating injuries because of the charge of the shot and accompanying gas that rapidly enters the head entering head. - Wadding may travel 5 to 10 feet and leave abrasion - Contact and close range wounds will have wadding in them - Wadding is hard to see on radiography because paper, plastic, cardboard

Pitfalls of Atypical Entrance Wounds

- Decomposed bodies - Survival interval (healing/suturing) - Clothing - Shored Gun Shot Wounds - Embalming artifacts - Bullet Emboli

Stopping power and rapidly fatal injuries

- Destruction of brain or upper spinal cord - Destruction of heart - Bleeding - internal or external - Blockage of airway by blood - Compression of organs (tamponade) - Collapse of lung - People can still function for several seconds even with a GSW to the heart - If head or spinal cord injury: immediate incapacitation. - Trunk wounds at acute angles may bleed very little externally due to closure of the wound track by the surrounding soft tissue.

Handguns

- Flint and lock percussion - Single shot pistols - Derringers - Revolver - Semiautomatic - pull of the trigger releases one bullet and loads another

Gunpowder and primer today

- Gunpowder: Nitrocellulose (Smokeless powder). Various shapes. - Typical Primer = Lead (Pb), Antimony (Sb), Barium (Ba) (THINK: "LAB") - this is what is tested for GSR

Manner of death in GSW

- Homicide: Common - Suicide: Common 20, 21 - Accident: Rare

Exit wound

- Irregular defect (linear/stellate) - Absence of fouling/stippling - Edges will re-approximate. - No margin of abrasion unless "shored exit" - Often larger than the entrance, but can be smaller

Scene Investigation

- Location and relationships (body to casings/projectiles) - Casings - Projectiles - Intermediate objects - Pictures are very important - Speak with everyone, document everything

Hollow point bullets vs. Full jacketed bullets

- No visible difference in wounding - An individual shot through the heart with a hollow point is just as likely to die as a person shot through the heart with non-hollow point handgun ammunition. - Hollow points tend to: > stay in the body. > break up if they hit a hard surface.

Fouling/stippling size, density, and appearance are depended on (8):

- Range - Propellant - Muzzle Angle - Barrel length - Caliber - Gun Type - Target Material - Attachments (silencers)

Guns that do not produce rifling

- Revolver without barrel - Smooth bore weapons - Starter weapons - Zip guns - Sympathetic discharge - Smaller caliber bullet than barrel

Quick summary of guns

- Rifled long gun - high velocity - Machine guns - fully automatic > submachine gun/pistol - fires pistol ammunition > machine gun - fires rifle ammunition

10 Gunshot wound tips

1. Always examine clothing and radiograph the body. 2. Determine wound tracks with the organs - remember positions of organs may have been different when the person was shot. 3. Caliber of the bullet may not equal entrance hole 4. Never confuse an exit wound and a contact entrance gunshot wound with blowback laceration. 5. Never estimate the caliber of the bullet from the autopsy x-ray. 6. Bullets (especially small caliber) may embolize aka go through the bloodstream 7. Do not wash down the body before looking for evidence of fouling. 8. If you aren't looking for stippling, you'll miss it (always look for it on the hands). 9. Shotguns: If there is a single entrance wound, most likely the wadding will also be in the wound. 10. Don't miss an intraoral GSW.

Kinetic energy lost by bullet depends on 4 things

1. Amount of KE before impact 2. Angle of yaw - movement around vertical axis (dont say tumble) 3. Bullet (caliber, construction, configuration) 4. Density/Strength of tissue

Atypical entrance wounds

1. Atypical projectile ballistics: faulty weapon/ammunition/high velocity weapons 2. Projectile deformation: ricochet, intermediate target, secondary projectiles. 3. Target contour variation: nose, lips, external ears 4. Target texture variation: hands, eyelids, scrotum 5. Re-entry wounds through apposed body parts

8 Things to come out of a gun

1. Bullet (wound) 2. Gas (effects seen in contact wounding) 3. Soot (Complete combustion of gunpowder): Fouling 4. Flame at 1400F (searing) 5. Burning & unburnt powder (Incomplete combustion of gunpowder): Stippling 6. Primer compounds - lead, antimony, barium 7. Copper/Nickel vaporized from cartridge case 8. Metal vaporized from bullet/jacket.

Range of Fire

1. Contact wound - tight/hard contact, muzzle stamp, blow-back lacerations, loose contact 2. Close range wound - fouling and stippling < 6" 3. Intermediate wound - stippling is present, but no fouling 6-30" 4. Distant (indeterminate) wound - beyond the range of stippling and fouling > 30"

Spread of shot depends on (7)

1. Distance/Range (under 2-3' all the same diameter) 2. Choke 3. Wadding: Inner lining of shell is meant to produce uniform dispersion so that a 16 yd target has the same spread as a 25 yd target. 4. Barrel length: Sawed off shotguns have negligible difference in spread compared to full length (nl 28-36") unless the barrel is sawed off to less than 9" (then greater spread). 5. Type of ammunition. 6. Shotgun diverter: attachment that makes circular shot pattern into rectangular shape. 7. Beware of the Billiard Ball effect!

Reason for autopsy

1. Documenting the wound 2. Determination > Range of fire > Direction of fire > Number and sequence of shots > Time and degree of disability after injury > Survival interval - getting shot, runs, and then collapses 3. Recovery of trace evidence 4. Recovery of bullet

Hollow point bullet

A bullet that is hollow - Designed to enter tissue and expand, to make no exit wound - Hooks develop when it expands to slow it down - Safer and made for law enforcement to prevent bullet exiting body and hitting bystander

Beveling

A conelike indentation created by an entrance wound in the skull or similar bone. - Tip of the cone points in the direction of the bullet

Bullet wipe

A gray or black ring around an entrance bullet hole from dirt/grease - mistaken for fouling

Shotgun range of fire as told by wounds

By defects on the skin - Close range = large entrance with no scalloping (scalloping is markings from the shot) > 0 to 2 feet - Intermediate = Can see scalloped edges on inside of wound > 2 to 4 feet - Far = scalloped edges with small entrance wounds or abrasions from the shot spread that didn't enter > 4 to 15 feet

Class v. Individual Characteristics in Ballistics

CLASS - Number, width, depth of twist and grooves. -Indicate make and model of gun. INDIVIDUAL - Imperfections on lands and grooves - Extractor, ejector, firing pin marks on cartridge - "This is the gun that fired that bullet"

Mechanisms of Injury

Cavitary effect - track created is much larger than bullet itself and has to do with spinning of bullet - Shock-wave effect of bullet relating to velocity - Surrounding tissue sustains damage several times larger than the bullet - Cavity diameter related to velocity - Temporary cavity: > Transient expansion of tissue causing laceration or contusion - sponges back but not completely - Permanent cavity: > Damage remaining after collapse of temporary cavity > Still larger than the bullet

Entrance wound

Circular - Size of GSW entrance is not equal to size of bullet - Because of stretching of skin, the entrance wound is usually smaller than the diameter of the bullet

*Gauge*

Classification system of shotgun barrel caliber - Diameter of shotgun barrel - Determined by the number of lead balls of certain diameter that weight one pound

Primer detection tests

Collect sample with paraffin or use swab soaked with weak acid to get sample of primer from hands 1. Walker Test aka Modified Griess: detects nitrates in clothing by blotting to photographic paper [shows presence as well as size and configuration of nitrates (orange-red spots)] 2. Paraffin/Dermal Nitrate Test: diphenylamine--> blue 3. Harrison-Gilroy: triphenylmethyl-arsonium iodide (Sb) + Na-rhodizonate (Pb & Ba) 4. Neutron activation (detects Sb & Ba; misses lead, need FAAS). Picks up 50% of handgun firings. Useless on Remington .22 which only has lead 5. FAAS (Flameless Atomic Absorption Spectroscopy): To be "positive" need all three with values of: Pb >800ng, BA >150ng, Sb >35 ng (may pick up some vaporized copper jacket) 6. SEM-EDX: Scanning Electron Microscope with Energy Dispersion X-ray Analysis: Shows shape and elemental analysis (Picks up 90% of handgun firings)

Billard Ball Effect

Do not estimate range of fire from the spread seen on an X-ray. - the pellets bounce off of each other and can randomly spread

Cylinder gap stippling/fouling

Due to the space between the cylinder (in revolvers) and the barrel. - See fouling or stippling on an object that is adjacent to the cylinder gap when a revolver is fired.

Temporary cavity

Formed after bullet is through - Determines extent of wounding > Tissue and blood can squirt out from the entrance and exit wounds. - Lasts milliseconds and then collapses - High velocity bullet fired at head --> bursts head BUT if high velocity bullet fired at empty skull --> small entrance and exit wounds w/out fracture.

Destructive force of projectiles

KE = 1/2mv^2 - more damage from increase in velocity not mass

Gunshot wound of head injuries

Skin - Blow back laceration - stellate tearing of the skin from force of gases > may mistaken entrance wound for exit wound Skull - Internal beveling (entrance wound); Outer beveling (exit wound) - Keyhole Skull wound: combined exit/entrance wound due to a shallow angle shot (almost a graze) > the bullet splits into 2 fragments as it perforates the bone (causes internal and external beveling in the same wound) > oblong and unusual shape - Gunpowder residue may deposit on outer table of skull or dura - Sequence determination - fracture lines will not cross the sutures (natural lines of the bone) and can help determine if a wound came before another one

Shored exit wound

Skin at site of exit wound is compressed by another object (e.g. the floor) so when the bullet exits, the skin around the exit wound gets scraped (it looks like an entrance)

Derringers

Small pocket firearms, typically with two barrels (each loaded and fired separately)

2 types of shotgun shots

Smaller the number = bigger pellet diameter 1. Bird - No. 12 (smallest) = 0.05" diameter with 2400 pellets/ounce 2. Buck - No. 4 (smallest) = 0.24" diameter with 27-54 pellets depending on load

Wad

Structural support consisting of cardboard or plastic - To seal off the gas produced by powder combustion for maximal velocity and as a cushion to prevent pellet deformation - Separates shot load from powder - Recovery of wadding materials at autopsy may be useful in identifying the brand of ammunition and the gauge of the weapon > tells you gauge and maker

False stippling

Suture removal, glass, insects, shotgun cartridge pellet packing

Retained bullets

Usually do not cause a health problem in a person who survives a GSW - However, if the bullet is near a joint, joint fluid can dissolve the lead and result in lead poisoning

Margin of abrasion

Virtually all handgun entrance wounds have a margin of abrasion (rim of abrasion). - Abrasion surrounding gunshot wound caused by bullet "scraping" skin. - It's a characteristic of entrance wounds.