CATA HOSA Introduction to forensic pathology
Dipteran life cycle: Post Feed Larvae?
(Maggot mass heating;larvae create own constant temperature) 1. Postfeeding larvae: migrate to seek protection perhaps under leaves or carpet 2. ADULT FLY BREAKS THROUGH THE PUPARIUM WITH AN INFLATABLE SACK ON THE HEAD CALLED PTILINUM WINGLESS MAY RESEMBLE A SPIDER 3. 3-5 DAYS AFTER EMERGING FLY WILL BE SEXUALLY ACTIVE (EMPTY PUPARIUM MAY RESEMBLE RAT DROPPINGS)
Bodies in shallow graves?
-Burial depths less than one foot: odors easily penetrate the soil -Odors attract insects and carnivores -Temperatures are similar to the surface -Bloating decomposition causes cracks in the soil -Plant roots grow toward corpse -May have differential plant growth at burial site -Roots may degrade clothing , tissue and cause grooving of outer bone cortex
What types of cases should be reported?
-Deaths resulting from violence -Sudden unexpected deaths -Environmentally related deaths -Decomposed bodies -Unknown or unclaimed individuals -Deaths from controlled substances -Deaths in prison or public institutions -Certain fetal and maternal deaths -Any death having to do with a child -Deaths under suspicious or unusual circumstances
What is mummificiation?
-Fluid loss via evaporation -Extremes of hot and cold -Skin is hard, leathery, forms a shell -Exposed parts of the body: fingers ,toes , face
What are the Stages of Decomposition?
-Fresh -Early -Advanced -Skeletonization
What are Tardieu spots?
-Pressure of lividity ruptures blood vessels causing skin hemorrhages -Takes aprox 18-24 hours -Indicates decomposition is rapidly approaching -Larger than petechiae
What damage can a rodent do to a bone?
-Produce parallel striae -May use human bone for nesting purposes -May transport bone -Continuously growing incisors -Upper incisors pressed into the bone while the lower incisors move up and down -Pedestal phenomenon: epiphyseal cartilage and adjacent areas of long bones
Dipteran life cycle:First Instar?
1. Adult female fly lay eggs on or near food (Need moisture and protection from solar radiation) -Nasal passages,corners of mouth or folds of clothing 2. Within a few hours eggs hatch into first instar,less than 2mm. Long
What is the postmortem change: Coagulation?
1. Blood becomes acidic from tissue breakdown 2. Causes activation of intrinsic coagulation pathway 3. Clots in arteries and veins 4. As decomposition progresses pH decreases activating fibrinolysis 5. Eventual reliquification of blood
Submerged Bodies?
1. Bodies in aquatic environment decompose at a rate approximately half that of decomposition in air (results from cooler temperatures and decreased insect activity) 2. Body resurfaces as decomposition ensues Water temperature determines when a body resurfaces (decrease in temp with depth) Salt and clean water decreases decomposition Aquatic animal life may alter decomposition
What is the postmortem change: Eyes?
1. Clouding of cornea 2. Tache noir: dark band of dried epithelium on the eye 3. Sludging and intravascular coagulation of retinal vasculature
What are the most common fly species (order diptera)?
1. Familly calliphoridae(blowflies) 2. Bluebottle flies 3. Greenbottle flies 4. Screwworm flies 5. Black blow flies
What are the steps in autolysis?
1. Hydrolytic enzymes released by lysosomes (triggered by a decrease in intracelluar PH) 2. Digest carbohydrates and proteins 3. Digest fats to a lesser degree (Begins sooner in organs with abundant lysosomes) 4. Skin slippage: release of hydrolytic enzymes at dermal epidermal junction 5. Bullae formation 6. Hair and nails do not grow postmortem 7. Marbling : intravascular hemolysis
What is the order of tissue decomposition?
1. Intestines, stomach, heart, blood, digestive organs 2. Air passages and lungs 3. Kidneys and bladder 4. Brain and nervous tissue 5. Skeletal muscle 6. Connective tissue
What is the importence of Forensic Entomology?
1. It is another way to show time since death 2. Season of death: pupae and exoskeletons may remain for months or years 3. Geographic origin of the remains: some species range in certain areas 4. Movement or storage of the remains: successive or intermitent broods of insects 5. Evidence of trauma: breaks in tissue provide high moisture content and protection 6. Presence of drugs: deposited in fat bodies and chitin of the exoskeleton
What do beetles do to postmortem body?
1. Most feed on fly eggs and larvae 2. Some feed directly on decomposing flesh: (silphids and dermestids) 3. Appear somewhat later than flies 4. May be some of the last insects to colonize a body 5. May be found in bone marrow or sinuses
What are the 5 Manners of Death?
1. Natural-death caused exclusively by disease 2. Accident-death caused by violent means, not due to the intentional or criminal act by another person 3. Suicide-violent death caused by an act of the decedent with the intent to kill himself 4. Homicide-violent death at the hand of another person due to a hostile or illegal act of that person 5. Undetermined-no determination regarding manner can be made after autospy and investigation
What occurs during and after Rigor Mortis starts?
1. R.Mortis occurs due to a lack of ATP in the muscle 2. Involves all muscles at the same time and at the same rate (most evident in smaller muscles and gradually becomes evident in larger muscle groups) 3. Post mortem ejaculation: RM in muscle of seminal vesicles 4.. Gooseflesh: RM in muscles of hair follicles RM may be inconsistent with gravitational forces indicating that the body was moved 5. Can be broken by passive stretching of muscles (once broken does not generally return unless it is only partially formed)
What do maggots do to postmortem body?
1. Regurgitate digestive enzymes into body producing semi solid material 2. When multiple maggots are present the enzymes act together to produce an almost liquid environment 3. Hardy external covering 4. The maggots are designed to move through this medium
How can scavening of remains by canines affect the result of postmortem findings?
1. Results in disarticulation and scattering of remains 2. Produces artifacts 3. Alter antemortem injuries 4. Removal of soft tissue of face and neck 5. Destruction of ventral thorax and upper extremities, clavicles 6. Lower limbs detached 7. Disarticulation of longs bone 8. Disarticulation, gnawing and scattering of all or most bones
What is the postmortem change: Other?
1. Uncontrolled growth of bacteria and fungi 2. Production of gases and aromatic organic compounds 3. Blood rich areas decompose first 4. Distortion of facial features 5. Distention of abdomen and scrotum 6. Gas bubbles may be seen in liver and other solid organs 7. Purge fluid: decomposed gastric lining and contents
What are some other arthropods that may feed on a body?
1. Wasps(hymenoptera) and ants are major predators of fly eggs and larvae 2. Cockroaches(dictyoptera): cause superficial feeding artifacts 3. Ants produce smaller feeding artifacts 4. Mites small and difficult to see
What is adipocere formation?
A soft, unctuous, or waxy substance, of a light brown color, into which the fat and muscle tissue of dead bodies sometimes are converted, by long immersion in water or by burial in moist places. It is a result of fatty degeneration. -Malodorous cheesy compound -May occur in a few days if warm and moist -Formation requires lipids -Longer periods in a dry environment -Hydrolysis and hydrogenation of fats to fatty acids
What are the 3 ways to determine Time of death?
Algor Mortis Rigor Mortis Livor Mortis
What may affect postmortem results?
Animal artifacts Insect activity Buried bodies Submersed bodies
What are the different types of Forensic Sciences?
Anthropology Odontology Entomology Botany Toxicology Ballistics
What is Cause of Death?
Any injury or disease that produces a physiological derangement in the body that results in the individual dying
How do you become a Coroner?
Elected Position May or may not be a physician
What is are the steps to completing an autopsy?
External Examination Internal Examination Microscopic Examination Toxicological Analysis
What is the fly life cycle?
Fly eggs (24 hours) Maggot (1 to 2 weeks) Pupae (1 week) Mature fly
What is needed in the collection of insect specimens?
Hand net Killing jar Thermometer Vials Forceps
What is Manner of Death?
How the cause of death came into being
What are some beetle artifiacts that are left behind?
Peritrophic membrane: protective covering on beetle fecal matter Produced by dermestid beetles PMI: months to years Remains were sheltered Drying and mummification
What damage can a canine do to a bone?
Produce a "v" shaped injury Punctures Pits Scoring Furrows
Dipteran life cycle: Third Instar?
Third instars need to increase in size, stores fat to prepare for metamorphosis Third instar: once fat stores are adequate, larvae migrate away from food source
What is the process of gastric emptying and digestion?
Time interval between eating and death Time varies depending on content of meal Great variability between different individuals Great variability between the same individual at different times
How do you become a Medical Examiner?
Usually an appointed position Almost always a physician Usually a forensic pathologist
What is the postmortem change: Autolysis?
cell self-decomposition. as the chemical change of shift in pH from alkaline to acidic membrane of lysosomes in cell rupture and spew digestive enzymes.
Putrefaction?
protein decomposition caused by anaerobic (without oxygen) bacteria Anaerobes : 96-99%of bacteria in colon, bacteroides,clostridia Aerobes: 1-4% enterococci,proteus
What is Forensic Botany?
the application of plant science to the resolution of legal questions.
What are the specific types of lividity and what causes them?
~Cherry red lividity: carbon monoxide poisoning, cyanide poisoning and cold temperatures ~Minimal lividity: hypovolemic shock or anemia
What are the Types of Decomposition?
Bloating Mummification Adipocere Formation
How does a Forensic Botanist use plants to make a determination?
By looking at ; Time, Pollen, Fungi, Algae,DNA ... Trace botanical evidence can link an object or suspect to the scene of a crime, as well as rule out a suspect or support an alibi. A plant's anatomy and its ecological requirements are in some cases species-specific; correct interpretation of botanical evidence can give vital information about a crime scene or the whereabouts of a suspect or victim
What is Rigor Mortis? Time Frame? Variables?
Definition: Stiffening of the muscles after death Time: Usually begins 2 to 4 hours after death Usually resolved by 36 hours Variables: Onset and duration variable Determined by ambient temperature Determined by metabolic state at the time of death
What is Livor Mortis? Time Frame?
Definition:Purple/red discoloration in the dependent areas of the body due to accumulation of blood after cardiac activity has ceased Time:Begins between 30 minutes to 2 hours after death Usually "fixed" by 8 to 12 hours after death
What is Algor mortis? Time Frame
Definiton:Decrease in body temperature after death Time:Body cools at a rate of 1.5 degrees Fahrenheit per hour for the first 12 hours then 1 degree Fahrenheit per hour for the next 12 to 18 hours
Buried Bodies?
Depths of four feet or more: skeletonization takes 2-3 years Depths of one foot: skeletonization takes 6 months Skeletal remains degrade quicker in wet environment or if too acidic or alkaline
Grave sites?
Disruption of plant growth Primary grave depression: outline of the grave from settling of the soil Secondary grave depression: bloating causes movement of soil followed by collapse
What are some maggot artifiacts that are left behind?
Larval bore holes Movement of remains by larval mass Maggot migration trails mimic drag marks
Burned remains?
May be a deterrant to some insects If burning results in cracking of the body that will give the insects better access to internal body surface
What are the products of decomposition?
Methane Hydrogen Hydrogen sulfide Carbon dioxide Alcohol Ammonia
What are the products of putrefaction?
Putrescine Cadaverine Biliverdin(green) Bilirubin(red) Urobilin(brown) Hydrogen Sulfide (black)
What occurs during and after Livor Mortis starts?
Red to purple as oxygen dissociates from hemoglobin of RBC's (deoxyhemoglobin: purple) -Unfixed pressure forces blood from capillaries resulting in blanching -Fixed: cooling solidifies dermal fat and closes capillaries ***Prior to becoming fixed lm will shift as the body is moved ***If person dies lying on their back lm develops posteriorly , if person is turned facedown lm will drain to anterior surface of body LM is fixed when shifting or drainage of blood no longer develops due to breakdown and hemolysis of BV's Can occur internally especially in the lungs.
What are some other fly species?
Sarcophagidae(flesh flies) Phoridae (humpbacked flies): conicera tibialis (coffin fly) Piophilidae(skipper flies) Muscidae(house flies
Dipteran life cycle: Second Instar?
Second instar results from the molting of first instar, for about 8-12 hours Second instar larvae feed more heavily, chemical composition changes from acid to alkaline which increases digestion of connective tissue and muscle
