Understanding the Process of Death and Forensic Entomology

1. THE PROCESS OF DEATH AND FORENSIC ENTOMOLOGY

2. The Process of Death • Pathologist determines time of death • Pretty accurate if body found within first 24 hours after death using the following indicators: • Algor mortis – cooling rate of body after death • Livor mortis – pooling of blood due to gravity after heart stops • Rigor mortis – rigidity of muscles after death

3. Algor Mortis • Cooling rate of body • Starting temp = 98.6 degrees • Begins equalizing temp of environment • Glaister Equation: used between 1 and 36 hours since death, most accurate within first 12h to determine time period since death based on body temperature Hours since death = 98.4°F – internal body temp 1.5

4. Must also consider: • Temperature of environment • Type and layers of clothing on body • Wetness of clothing • Air movement • The greater the surface area to mass ratio – body cools faster – e.g. children, small adults

5. Livor Mortis • “lividity” – discoloration; black and blue • Pooling of blood due to gravity after heart stops • Appears as purplish-red discoloration • Indicates position of body at time of death • Doesn’t occur in areas of body that are in contact with ground or constricted by other objects • Begins within ½ h. after death and most evident within first 12 h. • Used to determine if body has been moved after death

6. Livor Mortis

7. Rigor Mortis • Upon death muscles relax, ATP breaks down and muscles become rigid • Smaller muscles first (face, neck, jaw) • Occurs within few hours of death and is gone within ~30 h – then body becomes limp • Not 100% accurate - must consider: • Environmental temp • Dehydration • Muscle condition and their use before death

8. Rule of thumb in estimating time of death

9. Stages of Decomposition • Autolysis • Putrefaction • Black putrefaction • Butyric fermentation • Diagenesis

10. Autolysis • 0-4 days • appears fresh externally, but decomposing internally • Cells self-destruct due to no oxygen, increase in carbon dioxide, decrease in pH, and wastes accumulating • After a few days fluid-filled blisters appear and skin sloughs off

11. Putrefaction • 4-10 days • Soft tissues are destroyed by bacteria • Bacteria give off gases - bloating • Greenish skin • Horrible smells

13. Black Putrefaction • 10-20 days • Body is mass of fluids • Collapses as gases escape • Flesh creamy but exposed body parts black • Horrible smells • Fluids drain out of body

15. Butyric Fermentation • 20-50 days • Cadaver is drying out • Some flesh remains • Butyric acid – cheesy odor

16. Adipocere formation • Months to years after death • Yellowish-white, greasy wax-like substance • Forms as a result of the breakdown of fatty acids by a particular anaerobic bacterium • Occurs when: • Burial in moist, alkaline soild • High body fat of corpse • Burial in a casket within a vault

17. Saponification - “soap making”

18. Diagenesis • 50-365 days • Dry decay • May mummify • Bone is altered

19. Rough estimate – depends on temperature, moisture, scavengers, etc. #days to become skeletonized = 1285 avg temp °C So if a body is left in 20C (68F) it would take about 64 days for it to become skeletonized

20. Taxonomy • Classification system • Carolus Linnaeus (1707-1778) • Kingdom • Phylum • Class • Order • Family • Genus • Species

21. Kingdom Animalia Phylum Arthropoda Class Insecta Order Blattodea Family Blattidae Genus Eurycotis Species Eurycotis floridana Palmetto Bug

22. Three ways Entomology is used in Forensics • Urban entomology – affecting man and his environment (e.g. termite damage to a building) • Stored products entomology – insects infecting food • Medical Entomology – insects that inhabit human remains

23. Medical Entomology • Deals with necrophagousinsects – eat carrion (carcass of dead, decaying animal) • Dermestidae - family • Insects determine PMI – postmortem interval – time that has elapsed since a person died Carrion beetle

25. Insects of Death • Flies (Order Diptera) • Beetles (Coleoptera) • Some eat flesh, some eat other species of larvae (beetle or fly) on the flesh • Some rural, some urban • Some shade, some sun • Some nocturnal (usually beetles)

26. Red-legged Ham beetle Hister beetle

27. Other uses of insects • Presence of wounds – if maggots found on torso rather than in mouth, nose etc. • Place suspect at crime scene – e.g. if murder suspect had chigger bites and chiggers found to only be in that one area • Contraband trafficking may contain insects - can determine where it came from • Insects on front of a car may indicate where a person has been • Presence of drugs in a body may be detected by presence of drugs in maggots

28. Insect development depends on: • Temperature • Higher temp = faster growth • Requires a certain temp range – not too hot, not too cold • Growth rate in temp-time units = degree-days or degree-hours. Represent amt of heating/cooling needed to go from one stage to next (e.g. egg to second instar)