forensic death investigation final

stab wound

• Aka puncture wound

• Caused by a pointed object, typically having a sharp tip, when the object is forced into the skin (underlying tissues) with the direction of the force in a more or less perpindicular angle with the skin. Stab wounds are typically deeper (through skin and into body) than they are wide (on the skin surface)

incised wound

• Cut or slash

• Results when an object with a sharp tip/edge, makes contact with the skin (with or without associated underlying tissues), with the direction of the force in relation to the skin occurring in a more or less tangential fashion

• Typically longer than they are deep 

chop wound

• Considered a combined blunt and sharp force injury that is produced by a relatively sharp object wielded with a tremendous amount of force

• Object is often heavy and moving at a high rate of speed or with significant angular acceleration. Because of the larger amount of force, they have feature of both sharp and blunt force injuries

• Frequently have marginal abrasions and contusions, and sometimes lacerations

• Underlying fractures are also common with these types of wound

• Examples of objects that can cause these wounds

  • Crowbars

  • Claw hammers

  • Tomahawks

  • Axes

  • Hatchets

  • Industrial and farm machinery

3 dimensions of sharp force injury

• Length - is created by the cutting margin of the blade and depends on specific knife and how far it was inserted

• Width - width of the wound corresponds to the thickness of the blade

• Depth - only a rough estimate of the lengths of the blade due to compression of the body as a knife is inserted and will also depend on how deeply the knife is place 

5 major injuries associated with blunt force trauma

• Abrasions 

• Lacerations 

• Avulsions

• Fractures

• Contusions

abrasions

• Scrape on the skin causing a loss of the superficial layers of the skin. It is created by a force sliding across the skin or the skin sliding across a surface

• Superficial injuries can be described in 2 dimensions, length, and width

• Color

  • Yellow

  • Tan

  • Red brown

  • Yellow brown

• Can be patterned and have characteristic appearances due to the objects creating them

• May have directionality depending on how the force was applied. At the site, skin is superficially sheared and can be piled up with small skin tags where the force ends 

• May occur postmortem due to loss of the superficial layer of skin but will appear waxy yellow and with drying will be a light red color

what abrasion dimensions has

• length

• width

contusion

medical term for bruise

• Aka bruise

• Created by force being applied to the skin causing rupture of the small blood vessels and bleeding into the tissue under the skin surface

• Color of contusion can vary with its thickness, location, and how long it has been present 

• Color of bruise change due to breakdown of blood into its iron components and usually start in the red-purple range, transitioning to a yellow green then yellow brown coloration

• Dating is somewhat helpful to give a basis of injuries occurring over an extended period of time with evidence of healing of bruises

• In decedents biopsies of bruises can be performed and dated microscopically to a range of days

• May also be patterned

• 3 dimennsional, difficult to assess the depth based on only observation of the skin surface

• Most times are described in 2 dimensions: length and width

• Helpful to sub-classify the superficial contusions commonly seen in the elderly on the back of the arms and hands and call them ecchymoses

bruises are 3 dimensional but difficult to determine 3rd (depth) unless…

• difficult to assess the depth based on only observation of the skin surface

• cut into it, biopsy kind of

bruises have how many dimensions

3

types of asphyxia

• chemical

• mechanical

• environmental

chemical asphyxia

• Involves the Reaction between a chemical and tissue/cell that results in interference of oxygen uptake, release, and/or utilization. Examples of chemical asphyxiants include carbon monoxide, cyanide, and hydrogen sulfide

mechanical asphyxia

• Involves Some physical force or physical abnormality that interferes with the uptake and or delivery of oxygen. Most mechanical asphyxiants affect breathing or blood flow, the latter usually due to neck vessel or thoracic compression. Breathing an oxygen-deficient atmosphere is typically considered a type of mechanical asphyxia

environmental asphyxia

• When atmospheric oxygen is insufficient either due to exclusion, depletion, or displacement, environmental asphyxia can occur. This type of asphyxia is often considered a type of suffocation

suffocation

•  (smothering)

  • nose/mouth and/or upper pharynx are occluded by an object or body part in such a way that adequate breathing cannot occur. Examples include a pillow or hand over the nose and mouth, a gag, and a head encased by a plastic bag

aspiration

• Consists of inhalation of non bolus or nondiscrete foreign material (eg. regurgitatged stomach contents) or site inappropriate material. Site inappropriate material includes such things as inhaled blood secondary to trauma. When aspiration leads to death, the “cause of death” is attributed to the condition (disease or injury) that led to aspiration 

• A special type of aspiration is drwoning - drowning is defined by 2002 world congress on drowning as process resulting in primary respiratory impairment from submersion/immmersion in a liquid. The vast majority of drownings are the result of immersion/submersion in water

compression

• (traumatic) asphyxia

  • Involves the presence of external force on the chest and/or abdomen that prevents expansion of the chest that is necessary for proper breathing (e.g. constricting snake, overlying) or causes a rapid increase in intrathoracic pressure with consequent vascular pressure effects (e.g. car falling on top of a mechanic)

postural

• Caused by position of body or part of the body leading to airway restriction, vascular compromise or breathing fatigue (eg. upside down…)

ante-mortem

before death

peri-mortem

during death

post mortem

after death