Forensics - Wounds caused by pointed and sharp-edged weapons

Honors Forensics 1 class

4 categories of wounds caused by pointed and sharp-edged weapons

1. Stab wounds

2. Incised wounds (cuts)

3. Chop wounds

4. Therapeutic/diagnostic wounds

Stab wounds are produced by…

pointed instruments

In stab wounds, the depth of the wound track in the body…

exceeds its length in the skin

Most commonly used weapon n stab wounds:

a knife

What are the parts of a single-edge knife

Grip

Guard

Ricasso

Back

Spine

Edge

Point

Parts of a single-edge knife(image)

Langer’s lines

a pattern of elastic fibers in the dermis of the skin

If stabbed perpendicular to Langer’s lines:

fibers will pull apart the edges of the wound, creating a gaping wound

Stab wounds parallel to Langer’s lines:

will produce narrow slit-like wounds

Oblique wounds

Between parallel and perpendicular stab wound to Langer’s lines

asymmetrical/semicircular

Y- or L- shaped wound

irregular configuration of stab wounds caused by knife’s being twisted or movement of victim as blade is withdrawn

Most common reason for large, irregular knife wound

movement of victim as weapon is withdrawed

Pattern abrasion from the guard can be caused if

knife plunged with great force → full length of blade enters body

knife plunged straight in

mark from guard symmetrical

knife plunged downward angle

guard mark above wound

knife plunged upward angle

guard mark below wound

oblique stab wounds

(plunged from right)

guard mark on the right

perforation of the skin with a kitchen fork:

generally not possible

Phillips Screwdriver

very characteristic configuration

X-shaped point of blade will cause a circular wound w/ 4 equally spaced cuts

Fall through glass door

Glass can perforate sternum and aorta

one can never definitely link a knife to wound unless…

the tip of the knife has embedded itself in the body and broken off

Stab wounds of solid organs

bleeding only occurs after the knife is withdrawn due to pressure of knife prevents bleeding

Most fatal stab wounds are located in

left chest region

fatal stab wounds of the right chest usually involve injury to

right ventricle, aorta, or right atrium

fatal stab wounds of the abdomen (lower chest) usually involve injury to

the livor or a major blood vessel (like aorta, or vena cava)

less common stab wounds

head and neck

uncommon stab wounds

brain and spine

incised-stab wound

a stab wound that is converted to an incised (slashing) wound

Force required to inflict the fatal stab wound: (4)

1. The condition of the knife

2. The resistance offered by the different tissues/organs penetrated

3. The depth/length of the stab wound

4. Amount of clothing and its composition

Dull, irregular-edged, or nicked cuttting edge can produce…

an incised wound with irregular, contused, or abraded margins (b/c wound is caused more by pressure than by the cutting edge)

No bridging

wrinkle wounds

skin is wrinkled, in folds, so the cutting edge skips from crest to crest of the skin, leaving a string of cuts

hesitation marks

self-inflicted incision wounds

superficial incised wounds next to fatal incised wound

Defense wounds

wounds of the extremities incurred when an individual attempts to ward off a pointed/sharp edged weapon

Defense wounds are mos commonly found…

on the palms of the hands, due to attempt to grasp or ward off the knife

Chop wounds (definition)

produced by heavy instruments with a cutting edge (Ex. axes, machetes, meat clevers)

Chop wounds (indication)

Presence of an incised wound with underling comminuted fracture or deep groove n the bone

Perp pulls out weapon embedded into bone →

might give it a sharp twist, fracturing or breaking off the bone

Therapeutic or Diagnostic wounds

Wounds produced by medical personnel during the treatment of a patient

Common Examples of Therapeutic or Diagnostic wounds

Thoracotomy incision

Surgical stab wounds of chest for insertion of tubes or drains