Death Investigation Forensic Pathology A PDF

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Fall 2020 - word for word from slides ...

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DEATH INVESTIGATION FORENSIC PATHOLOGY A ORIGIN Pathos “suffering/disease” Logos “word/writing”  Studies disease, its causes, and its diagnosis  Specialized areas: o Anatomic – Autopsies and examine tissues o Clinical – Manage bodily fluid testing laboratories DUTIES OF FORENSIC PATHOLOGISTS  Investigate the deaths of persons who die suddenly and unexpectedly or as a result of injury  Normally employed by cities, counties or division of government  Some forensic pathologists work as consultants in litigation THE INVESTIGATION OF DEATH  Purpose: to determine cause and manner  Information needed to be able to draw conclusions  Presentation of physical evidence to support conclusions CAUSE AND MECHANISM OF DEATH  Cause of death- a disease or injury that initiated the lethal chain of events, however prolonged or brief, that led to death of the person  Mechanism of death- a biochemical or physiologic abnormality produced by the cause of death that is incompatible with life MANNER OF DEATH  The fashion in which the cause of death came to be  NASH o Natural - disease o Accidental - trauma o Homicidal - trauma o Suicidal – trauma TIME OF DEATH  Estimate using: o Rigor mortis – stiffening of the muscles  Chemical reaction of glycogen  Occurs 4 hours after and lasts up to 24 -36 hours o Livor mortis – discoloration of the body  Settling of red blood cells  Occurs 1 hour after and lasts up to 36 hours  Not always seen o Algor Mortis – cooling of the body  Nude body in 18-20oC drop 1.5oC per hour for first 8 hours  Ex: Normal body temperature is 37oC if dead for 4 hours temperature will be~31oC

Rigor mortis- stiffening of muscles which occurs following death: o Results from a chemical reaction with glycogen o Glycogen, normally used to provide energy for contraction muscles, is used up and not reformed o Rigor Mortis normally sets in about 4 hours after death o Exceptions include instant rigor mortis and death from electric shock. Both create shorter onset of rigor mortis from time of death o Rigor Mortis generally disappears 24-48 hours after death Livor Mortis - discoloration of body from settling of red blood cells after blood stops circulating, aka lividity.  In light skinned individuals, lividity may be seen within an hour after death  In dark skinned individuals, lividity may not be able to be seen  Substantial blood loss may result in little lividity  Lividity becomes fixed about 12 hours after death, and slowly disappears with decomposition after 36 hours Algor Mortis- cooling of the body after death, and assumes ambient temperature is lower than body temperature  General rule of thumb- a nearly nude body exposed to 18-20 degrees Centigrade loses 1.5 degrees in first 8 hours TOOLS OF DEATH INVESTIGATION Reviewing Medical history  Forensic pathologists deal primarily with determining cause of death, but also review past medical history to understand issues raised by that death  Medical history is the starting point of investigation Starting point  Determining jurisdiction o Two-pronged test  Sudden death  Unexpected  Treatment after death o Needle incisions, incised wounds, bone fractures Reviewing Witness Statements  Aids in determining jurisdiction  Questions to be answered  Refuting statements  Prejudicing judgment Scene Examination  Compensate with photographs and impressions  Questions answered by scene examination: o Post-injury movement o Time between injury and death o Time of injury and death o Time of unconsciousness o Other Death Related questions etc.

Autopsy Examination  Religiously forbidden o Judaism o Islam o Some Christianity  Next of kin  Jurisdiction of the coroner or M.E Autopsy Process  Incisions created in chest, abdomen and head  Removal of organs from those areas of the body  T-shaped incision is typically used, because it facilitates examination of tongue and neck    

Removal of organs Examination of brain Organs weighed and dissected o Underlying bruising Police custody

DOCUMENTATION AND SPECIMENS Toxicologists o Blood – Drugs/Alcohol o Urine - Drugs o Bile o Portions of internal organs - disease  DNA analysis o Blood and hair  Photographs MICROSCOPIC EXAMINATION  Small portions of organs are put into a solution of formaldehyde to preserve them for study  Diseased or injured sections of tissue are taken, as is normal tissue  Tissue is encased in paraffin wax  Sections mounted on slides  Stained with Haematoxylin & Eosin for examination under light microscope HISTOLOGY  compound of the Greek words: o histos "tissue “ o -logia "science “ o is the study of the microscopic anatomy of cells and tissues of plants and animals. HISTOLOGY STAINING Haematoxylin  A basic Dye  Stains Nuclei Blue due to affinity with Nucleic acids in the cell nucleus Eosin An Acidic Dye  Stains Cytoplasm Pink

DNA ANALYSIS  Most coroners and medical examiners preserve one specimen of tissue for DNA analysis  If tissue sits in formaldehyde for too long, DNA becomes hydrolyzed and unsuitable for study  DNA embedded in paraffin blocks or cut into sections and made into slides will not further decompose DNA COLLECTION  Methods to accomplish this: o Blood spotted on absorbent paper allowed to dry then stored in envelope o Pull head hairs, including bulbs, and place in envelope o Cut hair has mitochondrial DNA, bulbs include nuclear DNA PHOTOGRAPHY  Both film and digital photography are both used, depending on law enforcement jurisdiction  Multiple photographs must be taken REPORT PREPARATION  Forensic Pathologists provide a written report of each autopsy  Gross examination- can be seen by unaided eye  Microscopic examination- requires a microscope GROSS AUTOPSY REPORTS  Should contain information regarding: o Discussion of external examination o Medical treatment evidence on body o Evidence of injuries o Dissection technique o Diagnoses based on gross autopsy MICROSCOPIC EXAMINATION REPORTS  Dictated after gross autopsy report  Histology laboratory report takes several days to prepare  Additional time required for preparation of slides  

Toxicology report created by toxicologist, reviewed by forensic pathologist, and appended to autopsy report Forensic Pathologist may prepare a final summary of external examination, internal dissections, microscopic examination and toxicology report

INVESTIGATION OF TRAUMATIC DEATH  NASH  Mechanical  Thermal  Chemical  Electrical

MECHANICAL TRAUMA

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Mechanical trauma occurs when applied physical force exceeds the tensile strength of the tissue to which the force is applied Sharp force refers to injuries caused by sharp implements: knives, axes, swords, etc Blunt Force refers to injuries caused by blunt instruments: rocks, bricks, etc.

SHARP  Examination of incised wounds  Death by Exsanguination BLUNT/ FIREARM  High or low velocity  Penetrating or perforating  Skin defects o Stippling/Tattooing o Abraded SHARP VS BLUNT Sharp objects produce incised and stab wounds o Example- a stab wound by an object, such as a knife, which has more depth than its other dimensions Blunt objects produce lacerations o Example- a wound caused by an item such as a brick or stone, which creates significant damage MECHANICAL TRAUMA Other blunt force trauma  Transportation collisions – accidents  Characteristics o Lethal head injury o Contusions o Hematomas Exsanguination- death after a significant loss of blood - a major artery or the heart is damaged and blood loss occurs, and can occur in either sharp or blunt force trauma

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MECHANICAL TRAUMA  Exsanguination- death after a significant loss of blood - a major artery or the heart is damaged and blood loss occurs, and can occur in either sharp or blunt force trauma FIREARM INJURIES Firearm injuries are distinct due to type of weapon  Rifled weapons- rifles, handguns  Smooth bored weapons – shotguns and antique weapons Injuries produced are result of velocity of projectile  The extent of injury increases as the square of the velocity increases times the mass of the projectile Firearm projectiles cause blunt trauma Firearm projectiles are classified by their propellants:  Gunpowder  Smokeless gunpowder- nitrocellulose Most common suicidal and homicidal wounds are results of firearm blunt trauma Firearm projectiles are also measured by their velocity  Low velocity- 300 meters per second and below  High velocity- over 300 meters per second  High velocity projectiles create a lead snowstorm, which are white fragments of lead around missing tissue  Normally only rifles create high velocity wounds- exception is .44 magnum handgun Gunshot wounds can be classified in two manners  Penetrating- creates an entrance wound but not exit wound- projectile must be recovered from body to confirm this  Perforating – creates both an entrance and exit wound- no projectile recovered from body WHEN A FIREARM IS DISCHARGED:  A primer ignites smokeless powder  Rapid burning of smokeless powder creates a large amount of carbon monoxide, nitrogen dioxide, and other gasses  Force is created by rapid burning of gunpowder or smokeless gunpowder  Projectile is propelled by this force through barrel FIREARM INJURIES Distance each component of reaction travels is the basis for determining the distance of the barrel from the victim of the shooting  Gas is projected from barrel only a few inches and creates a near-contact wounds– which creates blackening of skin if victim is close to discharge of weapon  Skin will also show lacerations from force of gas Carbon monoxide from discharge mixes with hemoglobin and myoglobin in wound to produce carboxyhemoglobin and carboxy myoglobin, which are both bright red in color, compared to normal dull red color of hemoglobin and myoglobin HEAD INJURIES RESULTING FROM FIREARM DISCHARGES  Large lacerations are often characteristic of head contact wounds

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Explosion of the head and evacuation of the brain may occur as a result of gunshots that produce large amounts of gas

GUNSHOT ENTRANCE WOUND TYPES Contact Wounds Near Contact Wounds Intermediate Wounds Distant Wounds CONTACT AND NEAR CONTACT WOUNDS  Contact –Soot found in the wound  Near Contact - As the distance of the barrel away from the skin increases, gas diminishes, and only unburned powder and bullet can penetrate skin. Soot may be found around the wound INTERMEDIATE WOUNDS  Intermediate – Stippling is created by unburned powder on skin around defect produced by bullet  Handguns create stippling when held .5 centimeters to 1 meter away from skin DISTANT GUNSHOT WOUNDS  Lack smoke and powder effects  Comprised of a circular skin defect and rim of abraded skin around edges  Diameter of skin defect is some indication of diameter of bullet, but not always reliable due to differences in diameters of common bullets FIREARM INJURIES  Primary difference in size of distant gunshot entrance wound is elasticity of skin - younger people have more elastic skin  Gunshot exit wounds are typically lacerated but not always larger than the entrance wound ESTIMATING VELOCITY OF EXITING BULLET o Assess exit wound  Small, slit shaped wounds with few side lacerations are generally from bullets traveling at slow speeds  Exit wounds with many side lacerations generally have traveled at high speedsmilitary or hunting long arm rifles Exit wounds are supported or shored if victims wear tight clothing such as a heavy leather coat, or is against a material such as dry wall which will support the skin and allow penetration of the bullet Shored exit wounds appear to be remarkably like entrance wounds- one must closely note the rim of abrasion of the wound, as it is larger Entrance wounds are generally round due to being fired from a rifled barrel  Rotation of bullet during flight causes wound to be round or elliptical  Yawing - when a bullet enters a body sideways  Yawing does not normally occur, but can when bullet passes through a medium thicker than air

BLUNT FORCE TRAUMA  Blunt force trauma can result from motor vehicle accidents

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Generally, with exception of gunshot wounds, homicidal blunt force trauma in an adult requires lethal head injury – injuries to other areas rarely produce death In children, head injuries are most common, however, but chest and abdominal trauma with lacerations to spleen, liver and heart are seen Most common mechanism of death from blunt force trauma is drowning in blood that has aspirated into lungs Contusion- accumulation of blood in tissue outside the blood vessels- most commonly caused by blunt force trauma Pattern of blunt object may be transferred to person who is struck

Hematoma- A blood tumor. Blunt trauma to the head will often produce a “goose egg” swelling CHEMICAL TRAUMA Alcohol o Directly – central nervous system depressant  > 0.03 – improvement of reaction time  < 0.03 – slowing of brain function and reaction time  0.10 – vomiting; absorption stops  0.25* – coma if not stimulated  0.30* – deep coma and slow breathing  *Naïve consumers

CHEMICAL TRAUMA Drugs of abuse  Barbiturates, diazepam’s, and opiates  Produce coma followed by cessation of breathing and death  Exceptions – Marijuana and cocaine  At high doses – death from seizures, extremely high body temperatures, and uncontrolled quivering of the heart CARBON MONOXIDE CO  Odorless and colourless  Accidental, suicidal or homicidal  Death by asphyxiation  Cyanide Poisoning THERMAL TRAUMA  Exposure to excessive heat or cold may produce death  Exposure to either cause breakdown of body mechanisms that maintain body temperature around 37 degrees Celsius  Hypothermia death common in individuals who are intoxicated by alcohol: Alcohol increases loss of body heat and reduces appreciation of the cold Hyperthermia – heat related illness which can cause death  The ability to maintain homeostasis declines as people age  Thermal burns are wounds caused by hyperthermia- temperatures above 65 degrees C (140 F) will produce burns upon direct contact  People who die at fires most commonly die from inhalation of Carbon monoxide  People who die with only a 1-2% CO level in a burned structure is presumptive evidence they were dead or not breathing when fire started

ELECTRICAL TRAUMA Passage of electricity through a person may cause death by a number of different mechanisms  Low voltage AC current ( under 1000 volts) crosses the heart and ventricular fibrillation  Heart normally produces 300 quivers per minute  AC produces 3600 quivers per minute In high voltage exposures: Tetany  Electrical Burn o Portion o Portion occurs: result of flow of current through tissues which creates holes in membrane of cells. This creates a devastating loss of limbs in person exposed to high voltage Electrical current burns person in a fraction of a second ASPHYXIAS Interruption of oxygenation of the brain Drowning Conscious – Excitation phase  Hemorrhage  Water in sinuses and stomach  Hyper inflation Unconscious – No excitation phase Strangulation Manual vs ligature Findings Cornu, Hyoid Bone. Hemorrhage In manual strangulation, fracture of hyoid bone in neck is infrequent, and seen in elderly women who have osteoporosis, which makes fracturing the bone easier Ligature strangulation, whether by hanging or garroting, generally results in findings of a furrow in the neck Summary Forensic pathologist = decision maker Multiple sources of information u Medical and case history, scene information, autopsy results, toxicological testing u Goal – identify cause, manner, mechanism and time of death...