Forensic Pathology Outline

Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

Forensic Pathology - Subspecialty of pathology concerned with identification of remains and determination of cause and manner of death I

Deaths referred to the medical examiner A. Violent deaths (accidents, suicides, homicides) B. Suspicious deaths C. Sudden, unexpected deaths D. Deaths without a physician in attendance E. Deaths in a penal institution

II Cause of Death - The process that initiates a chain of events resulting in death A. Atherosclerosis ⇒ MI/arrhythmia B. GSW chest ⇒ pneumonia C. MVA ⇒ repair of aortic laceration ⇒ aneurysm at site 10 years later D. Blunt force injury of head ⇒ altered mental function ⇒ aspiration ⇒ pneumonia

III Manner of Death A. Natural 1. Atherosclerosis 2. Pneumonia 3. Cancer 4. Sequelae of ethanol/drug abuse 5. Perforation of gastric ulcer B. Accident 1. MVA 2. Ethanol/Drug overdose 3. Drowning 4. GSW 5. Asphyxia C. Suicide 1. GSW 2. Stab/incised wound 3. Drug overdose 4. Drowning 5. MVA 6. Asphyxia D. Homicide 1. GSW 2. Stab 3. Drug overdose 4. Drowning 5. MVA 6. Asphyxia E. Undetermined 1. Insufficient information about the circumstances surrounding death a. Drug overdose—accidental overmedication or suicide

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Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

2. Cause of death unknown a. Skeletonized remains b. No anatomical/toxicological explanation

IVScene Investigation

- Investigative/medical/legal conclusions rest on an intelligent and thorough scene investigation A. Identity B. Approximate time of death C. Important evidence/clues to circumstances surrounding death 1. Secure residence 2. Signs of struggle 3. Position of body/clothing 4. Suicide notes 5. Trash contents

V Identification of Remains A. Visual by relatives or friends B. Location of body (e.g. In home) C. ID cards distinctive feature (tattoo, ring, necklace) D. Scientific Identification 1. Ante mortem radiographs/medical records 2. Serology/DNA 3. Dental records 4. Fingerprints VI Chain of Evidence A. Item properly identified B. Item stored so as to prevent tampering C. Maintain record of what was done with object, by whom, at each change of hands VII Establishing Time of Death A. Witnesses B. Physical evidence (mail, newspaper) C. Post mortem changes 1. Putrefaction 2. Insect activity VIIIChanges Associated With Death A. Rigor Mortis 1. Depletion of ATP 2. Involves all muscles simultaneously and evolves at that same rate in all muscles 3. Most evident in small muscles first a. Classical presentation in order of appearance i. Jaw ⇒ upper extremities ⇒ lower extremities 4. Onset and disappearance dependent on many variables 5. No rigor—death < 3 hours 6. Developing rigor—death 3 to 9 hours

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Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

7. Full rigor—death > 9 hours 8. Passing rigor—death 24 to 48 hours a. Duration of rigor shorter in warm environment 9. Any activity or condition prior to death that results in decreased ATP accelerates development of rigor mortis a. Violent/heavy exercise (cadaveric spasm) b. Severe convulsions c. High body temperatures 10.May be delayed in: a. Very weak or emaciated individuals b. Infants c. Cold/freezing temperatures B. Livor Mortis 1. Mechanism—settling of blood in dependent areas of body a. Appears within 30 minutes after death b. Non-fixed/blanching (< 8 to 12 hours)—blood still within capillaries and will shift with change in position c. Fixed/non-blanching (> 8 to 12 hours)—blood within tissue and will not shift with change in position 2. Discoloration a. Purple—normal (venous blood) b. Green—sulfhemoglobin (hydrogen sulfide) c. Pink, cherry-red i. Carboxyhemoglobin (carbon monoxide) d. oxygen (cyanide, hypothermia, refrigeration) 3. Important in determining post-mortem movement of body, not time of death 4. May be confused with bruising a. Bruises do not blanch with pressure 5. Fixation may be delayed by cool temperatures C. Algor Mortis 1. Cooling of body by heat transfer following death a. Conduction—direct contact b. Radiation—infrared rays c. Convection—air currents 2. Inner core temperatures preferred—decline is slower/regular a. Rectal b. Liver c. Brain 3. Skin—cools rapidly from exposure to environment, so not useful 4. Under average conditions a. < 3 hours—2.0° F to 2.5° F / hour b. 3 to 12 hours—1.5º F to 2.0º F / hour c. 12 to 18 hours—1.0º F / hour d. Tables useful, but must be used within context of case e. Data tables assume: i. Peri-mortem temp 98.6 ii. Constant post-mortem temp iii. No extremes in environmental temp iv. Other scene variables

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Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

D. Decomposition 1. Fresh 2. Bloated 3. Active 4. Dry/skeletal 5. Bloated stage a. ~ 36 to 48 hrs—marbling (breakdown of blood within veins) and skin slip/blistering b. ~48 hrs—bloating (gas production) c. ~48 to 72 hrs—green to black discoloration 6. Active decay a. 3 days to several weeks i. Variables: temperature, insect activity, bacteria 7. Dry/skeletal stage a. 2 weeks in hot humid temps b. Months in snow c. Years if body changed by adipocere E. Animal Activity 1. Land 2. Sea F. Preserving Changes 1. Mummification a. Drying of body—usually in warm/dry climate b. Skin preserved, internal organs not always 2. Adipocere a. Waxy change of fat—usually in high humidity/water b. Conversion of unsaturated fatty acids to saturated fatty acids via Clostridia enzymes G. Accelerating Changes 1. Injury sites—allow access to insects 2. Anything that promotes warmth a. Obesity b. Heavy clothing c. Sepsis IX SIDS A. Natural Death—SIDS 1. Usually occurs within 6 months, no more than 10 months 2. Exact mechanism unknown a. Not caused by smothering or choking 3. Not contagious 4. Not hereditary 5. Occurs very quickly and is assumed to happen during sleep—no suffering or distress B. Natural Death Presenting As SIDS 1. Pneumonia 2. Pyelonephritis 3. Myocarditis 4. Bacterial meningitis 5. MCAD deficiency 4/12

Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

C. Other Cases Presenting As SIDS 1. Accidental suffocation 2. Child abuse

X Asphyxia - Anything that interferes with oxygen uptake or utilization A.Suffocation – failure of oxygen to reach blood

1. Smothering—mechanical obstruction of nose and mouth a. Plastic bag b. Hand c. Overlying (can’t distinguish from SIDS) 2. Choking—requires an underlying explanation a. Intoxication b. Neurological disorder c. Psychiatric patient d. Aspiration of food e. Foreign objects 3. Drowning a. Dry vs. wet drowning b. Need to determine why person drowned 4. Suffocating gases – displacement of oxygen, i.e. Hydrogen sulfide gas B. Mechanical asphyxia--compression of chest 1. Car/other heavy objects 2. Bodies (riots, stampedes) 3. Positional asphyxia a. Cribs with mismatched mattresses b. Intoxicated adults C. Strangulation 1. External pressure causing closure of the blood vessels and trachea 2. Pressures a. 4.4 lbs.—jugular veins b. 11 lbs.—carotid arteries c. 33 lbs.—trachea 3. Hanging a. Usually suicide b. Point of suspension c. POS superior to laryngeal prominence 4. Ligature a. Usually homicide b. Transverse mark c. Evidence of a struggle i. Conjunctival petechiae ii. Contusion of strap muscles iii. Fracture of hyoid bone or superior horns of thyroid cartilage 5. Manual a. Homicide b. Neck holds (law enforcement)—usually no external injury unless flashlight or baton used

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Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

i.

Carotid sleeper hold—obstruction of blood flow (i) Rapid onset of unconsciousness—must release immediately upon incapacitation (ii) Release—complete recovery in seconds ii. Choke hold—airway compression (i) Serious damage/death within seconds (ii) Muscular or subcutaneous hemorrhage D. Chemical asphyxia 1. Cyanide—almond odor a. Cherry red discoloration of tissues 2. Carbon monoxide a. 50% carboxyhemoglobin lethal level b. Cherry red discoloration of tissues c. Quick (6 to 7 minutes) d. Children and elderly especially sensitive XI Burns A. Categories 1. Flame 2. Contact 3. Radiant heat 4. Scalding 5. Chemical 6. Microwave B. Rule of nines 1. Head—9% 2. Arms—9% (each) 3. Anterior torso—18% 4. Back—18% 5. Legs—18% each 6. Neck or perineum—1% C. Degree of injury 1. 1st degree—confined to epidermis a. Skin red without blistering 2. 2nd degree—destroys epidermis, spares dermis a. blistering 3. 3rd degree—destruction of dermis a. Skin surface brown or black 4. 4th degree—destruction of subcutaneous structures (e.g. muscle) D. Clothing is protective E. Death 1. Immediate—smoke inhalation 2. Delayed—sepsis from burns F. Must establish 1. Identification of deceased 2. Whether deceased was alive at the time of fire 3. Cause of death 4. Manner of death 5. Any contributing factors

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Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

a. EtOH, drugs, natural disease G. 75% of fire-related deaths due to inhalation of toxic smoke 1. Carbon monoxide (lethal level 50%) a. Children/small animals reach fatal level quicker due to higher metabolic rate 2. Hydrogen cyanide (lethal level 5 mg/ml) H. Appearance of victims 1. Weight and height altered 2. Feet and hands may be lost 3. Pugilistic pose—shrinkage of muscle 4. Body of an adult rarely destroyed by house or car fire a. House fire temp—1200 to 1600 F b. Crematorium temp—1800 to 2000 F 5. Children may be consumed by fire I. Artifacts of burns 1. Epidural hematoma 2. Fire fractures of bone J. Scalding 1. Immersion 2. Splash 3. Steam K. Chemical burns 1. Acids (HCL) 2. Bases (lye, bleach) 3. Petroleum products (blistering) XII Electrocution A. Ohm’s law—V=IR (volts = current x resistance) B. Household current 110 volts (alternating) C. Resistance of skin 1. Dry—100,000 ohms (1.1 mamp) 2. Wet—1,000 ohms (110 mamp) D. Low voltage 1. Burns usually present at entry/exit sites a. Caveat—current entering over broad surface, e.g. bathtub electrocution 2. Death due to ventricular fibrillation E. High voltage 1. Electrical burns—chalky white with cratering 2. Charring 3. Death due to ventricular standstill or paralysis of respiratory center F. Lightning 1. Direct strike 2. Side flash 3. conduction

G. Death from high-voltage direct current is usually due to burns and injury to respiratory center of brain XIIIGunshot Wounds A. Mechanics of firing 7/12

Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

1.

Firing pin ⇒ ignition of primer ⇒ ignition of gunpowder ⇒ creation/expansion of gas ⇒ bullet, unburned powder, soot propelled down barrel of gun B. Entrance wounds 1. Characterized based on distance of gun from victim a. Contact b. Close range c. Intermediate d. Distant 2. Contact a. Muzzle imprint b. Stellate lacerations (if adjacent to bony structure) c. Gunpowder and soot enters wound 3. Close range—within 3 inches a. Increase in distance = increase in diameter of particle deposition and tattooing around entrance wound and decrease in particle density b. Entrance wound i. Particles of gunpowder around wound ii. Soot on skin iii. Tattooing (stippling) of skin 4. Intermediate range—3 to 36 inches a. Further increase in diameter of particle deposition and tattooing around entrance wound and further decrease in particle density b. No soot 5. Distant range—greater than 36 inches a. Absence of gunpowder particles, soot, tattooing b. Difficult to determine exact distance—appearance of GSW inflicted at 6 feet doesn’t differ from one inflicted at 16 feet. c. Using the exact same gun and ammunition a ballistic expert can experiment to determine the distance. 6. Other entrance wound characteristics to look for include: a. Usually smaller than exit wounds unless: i. Located adjacent to bony structures (stellate) ii. Bullet deflected prior to entrance b. Inward beveling of skull c. Rim of abrasion C. Exit Wounds 1. Usually larger than entrance wounds due to deflection of bullet by tissues 2. Outward beveling of skull 3. No gunpowder particles, soot, tattooing 4. No rim of abrasion a. Exception: shoring of exit 5. Wound may appear slit like D. Shotgun Wounds 1. Contact—circular wound with muzzle imprint 2. Close a. Circular wound < 2 feet b. Scalloped edges at 3 feet 8/12

Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

c. Few stray pellets at 4 to 5 feet 3. Intermediate—6 to 7 feet a. Rim of pellets b. Wad abrasion 4. Distant—> 10 feet a. complete spread of pellets XIVBlunt Force Injuries A. Mechanism—tearing, shearing, crushing B. Categories 1. Contusion 2. Abrasion 3. Laceration 4. Fracture C. Contusion—hemorrhage into the soft tissue surrounding the wound 1. No bruise if blow from wide/smooth object or in area protected by heavy clothes/hair 2. Patterned a. Steering wheel imprint on chest b. Parallel (train-track) lines from rod, stick, whip c. Horseshoe shaped—whipping with looped cord 3. If death occurs quickly, no bruise evident—must incise area to detect hemorrhage 4. Color change with time—from periphery to center 5. Color change may be used to “age” the injury—depends on size, extent, depth, local circulation a. Immediately—slight swelling b. Few hours—light blue/red c. Week—dark purple, greenish-yellow 6. Variables which increase bruising a. Children and elderly i. Senile ecchymoses on forearms of elderly b. Obese women c. Alcoholics with cirrhosis d. Aspirin/Anticoagulant use 7. Maybe be produced postmortem if severe blow delivered within a few hours of death a. Rare b. Most common in skin/soft tissue overlying bone 8. Iatrogenic a. Surgical removal of corneas or globes b. Removal of vitreous 9. Decomposed bodies a. Hemolysis of erythrocytes may mimic contusions b. Hemolysis of erythrocytes in genuine contusions also occurs— may be impossible to differentiate between decomp and contusion D. Abrasion—scraping/removal of superficial layers of skin 1. Graze—bullet 2. Scratch—fingernail, sharp edge 9/12

Forensic Pathology Outline 2005

E.

F.

G.

H.

Elizabeth J. Miller, M.D.

3. Brush burn—frictional force (dragging on ground) 4. Binding—handcuffs/rope 5. Patterned a. Weave of clothing b. Threaded pipe c. Wood grain of baseball bat d. gravel Laceration—blow from blunt objects or falls 1. Bridging of connective tissue within depths of wound 2. Age determination difficult 3. Appearance may not reflect object causing injury 4. In general a. Long, thin objects cause linear injury b. Flat objects cause irregular, ragged, Y-shaped injury 5. Explore depths of wound for foreign material 6. Determination of direction of wounding a. Abrasion/beveling—side from which blow delivered b. Undermining of tissue—side away from which blow delivered Fracture—direct or indirect force on bone 1. Direct a. Focal—small force applied to small area b. Crush—large force applied to large area c. Penetrating—large force applied to small area 2. Indirect—force acting at distance a. Traction—violent contraction of quadriceps m. b. Angulation—bending resulting in transverse fracture c. Rotational—twisting resulting in spiral fracture 3. Skull fracture, base—usually run in direction of impact a. Ring fracture—separation of rim of foramen magnum from remainder of base i. Fall from height onto feet or buttocks b. Transverse—side-to-side) i. Impact either side of head ii. Side to side compression c. Longitudinal—front to back i. Impact on forehead, face, back of head ii. Front to back compression 4. Skull fracture, base a. Bleeding from ears, nose or mouth b. Hemorrhage into soft tissue of eyelids—raccoon eyes c. Hemorrhage into soft tissue behind ears—Battle’s sign Brain contusion 1. Coup—occur at site of injury a. Blow to the head 2. Contrecoup—occur directly opposite to the point of impact a. Classically associated with falls b. Frontal and temporal lobes c. Virtually never occur in occipital lobe Intracranial hematoma 1. Subarachnoid

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Forensic Pathology Outline 2005

I.

Elizabeth J. Miller, M.D.

a. Most common sequela of head trauma b. Focal or diffuse c. Traumatic i. Laceration of veins—most common ii. Laceration of internal carotid, vertebral, basilar aa. 2. Epidural hematoma – trauma to skull with rupture of artery at point of impact a. Primarily impact injuries—falls, MVA’s b. Blood intervenes between dura and inner table skull c. A fracture is usually present—squamous-temporal bone d. Usually confined to side of impact e. Presentation of symptoms i. Usually 4-8 hours following injury ii. Sometimes as soon as 30 minutes or as late as 36 to 48 hours f. Lucid interval prior to development of symptoms g. Death due to displacement of brain (mass effect) with brain stem compression 3. Subdural hematoma—acceleration/deceleration injury a. Stretching/tearing of bridging veins b. Most common lethal injury from head trauma c. Usually not associated with fractures d. May occur in absence of obvious sign of trauma e. Acute—symptomatic within 72 hrs f. Subacute—symptomatic between 3 days and 2-3 weeks g. Chronic—symptomatic after 3 weeks 4. Onset of symptoms usually acute (30 minutes) a. Life threatening at 50 ml b. Displacement of brain (mass effect) with brain stem compression Motor vehicle accidents 1. Patterned abrasions—steering wheel 2. Dicing 3. Seat belt 4. Aortic transection distal to subclavian artery 5. Fat embolism

XV Sharp Force Injuries A. Stab wound 1. Usually homicide 2. Length/depth of wound track > width 3. Edges usually without abrasion/contusion 4. Size and shape depends on many variables a. Type of weapon—knife, ice pick, screwdriver b. Configuration of weapon c. Direction d. Movement of blade in wound e. Langer’s lines—elastic fibers in skin 5. Appearance of wound margins depend on sharpness of knife 6. Determination of angle 11/12

Forensic Pathology Outline 2005

Elizabeth J. Miller, M.D.

a. Oblique angle—beveled margin on one side/undermining of skin opposite side 7. Determination of edge a. Single edge—squared off edge/sharp edge b. Double edge—both edges sharp 8. Mechanism of death a. Exsanguination b. Tamponade c. Complications (infection) B. Incised wound 1. Longer than deep 2. No bridging (differentiate from laceration) 3. Usually suicidal a. Hesitation marks/scars 4. Usually not fatal 5. Homicidal incised—neck a. Inflicted from behind i. Begins high on neck opposite side of cutting hand ⇒ downward ⇒ straight across midline ⇒ upward, ending on opposite side of neck lower than initial point ii. wound first shallow, then deeper, then shallow 6. Suicidal incised—neck a. Inflicted from front i. Short and angled ii. Right handed—wounds on left side of neck iii. Slashes downward and medial at oblique angle C. Chop wound 1. Incised wound with underlying injury to bone 2. Incised and lacerated characteristics a. Cutting and crushing 3. Weapon Used a. Axe b. Machete c. Cleaver d. Hoe D. Therapeutic/diagnostic wounds 1. Surgical stab wounds a. Chest tube b. Abdominal drain c. Thoracotomy/lapartomy incisions d. Cutdowns of wrist/antecubital fossae, e. Tracheostomy incision

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