Forensics & autopsy
Types of injuries
Fire deaths
Author: Lindsey Harle, M.D.
Topic Completed: 1 July 2013
Minor changes: 29 July 2020
Copyright: (c) 2012-2019, PathologyOutlines.com, Inc.
PubMed search: Forensics fire death
Table of Contents
Definition / generalCite this page: Harle L. Fire deaths. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/forensicsfiredeaths.html. Accessed August 10th, 2020.
Definition / general
Classification of burns:
- 1st degree: limited to superficial epithelium; erythematous with pain, edema, skin peeling; does not scar
- 2nd degree: involves full thickness epidermis and superficial dermis; skin appendages are spared; blistering, painful; usually do not scar
- 3rd degree: involves all skin layers, including full thickness dermis and skin appendages; no pain due to nerve injury; appears white; severe scarring
- 4th degree: complete destruction of skin, subcutaneous tissue and possibly bone
- Extent of injury recorded as percentage of body surface area; use rule of 9s in adults, chart #2
- Age adjusted body surface area chart for children; use rule of 5s for infants and young children
- Heat intensity, duration of exposure, presence / absence of clothing
Types of burns
- Flame: occurs when skin is in direct contact with flame
- Flash burn is due to sudden explosion of gas or particulate matter; produces uniform burn over all exposed skin
- Contact: occurs when skin is in direct contact with a hot object (e.g. iron)
- May show pattern injury reflective of the hot object
- Radiant: occurs when skin is exposed to heat waves; produces blistering and erythema
- Scalding: occurs when skin contacts hot liquid
- Immersion burn: occurs commonly when child is placed in tub of hot water
- May indicate child abuse; as child flexes to avoid water, areas of skin are spared around knees and inguinal region
- Splash or spill burn: cased by splashing of hot liquid; usually accidental in nature
- Burn pattern should correspond to the scene description, with more severe burns near the initial point of contact (e.g. child’s hand or head when a pot of liquid is pulled off the stove)
- Steam burn: can cause severe laryngeal edema when inhaled
- Microwave: occurs when skin is exposed to electromagnetic waves; usually accidental
- Tissue with higher water content shows more severe injury (e.g. muscle burns more rapidly than fat)
- Chemical: occurs when strong acids or alkali contact skin; can also be caused by phosphorus or phenol
- Burns develop more slowly than those created by thermal injury
- Alkali agents tend to cause more severe injury; are usually full thickness and appear pale and leathery
- Acid burns usually are partial thickness and appear erythematous and erosive
Mechanism of death
- Immediate mechanism of death due to thermal injury
- Neurogenic shock secondary to severe pain
- Hypovolemic shock and acute renal failure due to loss of fluid from skin
- Toxic gas inhalation - CO (most common), cyanide, acrolein, nitrogen dioxide, hydrochloric acid
- Often see soot in nose / mouth
- May produce edema, mucosal necrosis of upper airway, or bronchospasm
- CO levels usually 30% - 60% in fire deaths
- Delayed mechanism of death due to thermal injury
- Delayed hypovolemic shock with renal failure
- ARDS
- Infection (pneumonia, sepsis, cutaneous)
- Pulmonary embolus due to immobilization
Postmortem changes in charred / burned bodies
- Pugilistic attitude: flexion of the upper extremities as the body cools
- Does not reflect ante- or perimortem body position
- Skin / muscle splits: occur parallel to muscle fibers; can extend into body cavities
- Should not be confused with antemortem trauma
- Loss of fingers / toes / extremities: due to charring or loss at the scene
- Heat epidural: blood boiling out venous sinuses produces postmortem epidural blood pooling
- Weight and length measurements are unreliable
Classification of fire deaths
- Death due to an intentionally set fire is generally a homicide
- Suicidal if the individual sets him / herself on fire
- Look for accelerants or volatiles on clothing from the decedent
- Many fires are accidental
- Antemortem versus postmortem burn
- Postmortem burns may appear yellow and dry; microscopic evaluation should reveal no inflammatory reaction
- Some postmortem burns can be impossible to distinguish from antemortem burns
