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Questions and Answers
Which of the following characteristics is associated with mummification?
Which of the following characteristics is associated with mummification?
Putrefaction begins affecting the upper abdomen first after death.
Putrefaction begins affecting the upper abdomen first after death.
False
What process involves the transformation of body tissues into a waxy substance due to fat decomposition?
What process involves the transformation of body tissues into a waxy substance due to fat decomposition?
Adipocere Formation
During __________, the body produces green, purple, or black discoloration due to bacterial activity.
During __________, the body produces green, purple, or black discoloration due to bacterial activity.
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What is the most common indication of time of death derived from algor mortis measurements?
What is the most common indication of time of death derived from algor mortis measurements?
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Match the decomposition process with its characteristic:
Match the decomposition process with its characteristic:
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Skeletonization occurs quickly after death and is characterized by the immediate exposure of bones.
Skeletonization occurs quickly after death and is characterized by the immediate exposure of bones.
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What is the environmental condition primarily needed for adipocere formation?
What is the environmental condition primarily needed for adipocere formation?
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What is the first sign of decomposition observed in the body?
What is the first sign of decomposition observed in the body?
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Adipocere formation can occur only in extremely cold environments.
Adipocere formation can occur only in extremely cold environments.
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What is the average rate of skeletonization under typical conditions?
What is the average rate of skeletonization under typical conditions?
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The process of transformation of fatty tissues into a waxy substance is known as __________.
The process of transformation of fatty tissues into a waxy substance is known as __________.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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What is the primary characteristic of mummification?
What is the primary characteristic of mummification?
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Beetles are among the first insects to arrive at a fresh corpse.
Beetles are among the first insects to arrive at a fresh corpse.
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Name one common insect used in forensic entomology for estimating time since death.
Name one common insect used in forensic entomology for estimating time since death.
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In the ________ stage of decay, large masses of maggots are still feeding on the corpse.
In the ________ stage of decay, large masses of maggots are still feeding on the corpse.
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Match the following stages of insect succession with their characteristics:
Match the following stages of insect succession with their characteristics:
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How long does the total maturation time for Calliphora vicina typically take at 22°C?
How long does the total maturation time for Calliphora vicina typically take at 22°C?
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Different species of insects have the same habits regardless of their environment.
Different species of insects have the same habits regardless of their environment.
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What is one factor that can significantly affect insect succession in a corpse?
What is one factor that can significantly affect insect succession in a corpse?
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Study Notes
Post Mortem Changes
- Postmortem changes are the physical and chemical changes that occur in a body after death.
- Decomposition stages are orderly physico-chemical changes after death.
- The rate of each change varies and is influenced by environmental factors.
- The longer the postmortem interval (PMI), the less precise the estimate of the time of death becomes.
Important Terminology
- Postmortem: Occurring after death.
- Perimortem: Occurring at the time of death.
- Antemortem: Occurring before the time of death.
- Death: Cessation of vital life functions.
- Somatic Death: Cessation of vital life functions.
- Cellular Death: Cell and tissue death, without metabolic activity.
- Brain Death: Irreversible brain damage, unresponsive to stimuli, absence of spontaneous muscle activity, and an isoelectric EEG.
Tony Bland - Hillsborough Victim
- Tony Bland suffered severe brain damage due to the Hillsborough disaster.
- He remained in a persistent vegetative state (PVS) for three years.
- His life support machine was switched off in 1993.
- His death occurred in 1993.
Post-Mortem Changes and TSD
- Postmortem changes include physical and chemical changes.
- These changes have different time factors (rates).
- Environmental factors such as temperature, exposure, and presence of insects and animals significantly affect the rate.
- More time elapsed from death result in less precision in determining the time of death.
Post-Mortem Changes in the Eye
- Loss of corneal and light reflexes.
- Fixed, unresponsive pupils (mid-dilated).
- Decrease in eyeball tension.
- Softer eyeballs after death.
- Loss of corneal reflectivity.
- Sclera discoloration in open eyes.
Post-Mortem Hypostasis
- Skin discoloration after death due to blood settling.
- Also known as lividity, staining, cogitation, and livor mortis.
- Hypostasis is gravity-dependent.
- Pale areas may appear where the body is in contact with the ground or tight-fitting clothing.
- The colour of livor mortis can differ based on the cause of death or environmental conditions.
- Typically red-purple.
- Cherry-red in cases of carbon monoxide poisoning or exposure to cold environments.
- Brown livor seen in chemical poisonings like sodium chlorate.
- Green livor in hydrogen sulfide exposure.
Livor Mortis Modification
- Faint/inapparent livor in cases of anaemia or in dark-skinned individuals.
- Fixation time varies based on temperature.
- Warmer temps lead to faster effects.
- Cooler temps lead to slower effects.
Evaluating Livor Mortis
- Evaluating livor mortis requires assessing location, distribution, color, fixation (blanching), and appropriateness with body position.
Rigor Mortis
- Progressive stiffening of the muscles after death.
- Starts in small muscles and spreads throughout the body.
- Body stiffening occurs in stages. - 3–6 hours after death - Maximum within 6–12 hours, remaining up to 18-36 hours - Rapid onset in children and elderly compared to young adults
- Environmental temperature, muscular activity before death, and disease states can affect the onset and duration of rigor mortis.
Factors Affecting Rigor
- Environmental temperature
- Degree of muscular activity before death.
- Onset of rigor mortis differs in children, the elderly, and young adults.
- The stage is faster in diseases like infections or wasting diseases.
- Delayed onset in some cases like asphyxia.
Spot Check in Average Temperature Conditions
- Warm and flaccid: less than 3 hours after death.
- Warm and stiff: 3–8 hours after death.
- Cold and stiff: 8–36 hours after death.
- Cold and flaccid: over 36 hours after death.
Cadaveric Spasm
- Instantaneous rigidity at the time of death.
- Cause is often unknown, possibly linked to violent or emotionally charged deaths.
- Typically affects specific groups of muscles. - Firmly grasping objects like knives - Grasping weeds in drowning deaths
Pugilistic Attitude
- Typical postmortem body position for victims of high-temperature exposure.
- Caused by muscle protein coagulation from extreme heat exposure (burning victims.)
Algor Mortis
- Cooling of the body after death due to the loss of body heat to the environment.
- Core temperature measurement (rectal or liver) is used to estimate TOD.
- Surface temperature measurement is less accurate.
- Equation (Glaister equation) estimates hours elapsed after death: (98.4 minus rectal temp.) divided by 1.5 equals hours.
- Factors Affecting Rate: - Age, body mass and surface area - Physical condition - Initial body temperature - Environmental factors (temperature, climate, clothing, exposure)
Body Cooling
- Body cooling is a physical process following Newton's Law of Cooling.
- The rate of cooling is dependent on the difference between body surface temperature and environmental temperature.
Late Postmortem Period
- Over 24 hours post death
- Process of decomposition
- Two main processes: Putrefaction and Mummification
Decomposition
-
Putrefaction: Bacterial activity leads to tissue break down.
- Results in green/purple/black discoloration, skin slippage, gas production, and bloating; and marbling (blood vessels).
-
Mummification: Dehydration or desiccation preserves tissues for a long time.
- Body withers and shrivels, skin becomes leather-like, splits, darkens
Putrefaction
- Putrefaction begins with environmental impact and occurs when death happens.
- First discoloration is in the lower abdomen, and is followed by green skin.
- Bacteria growth starts with 24–36 hours after death and the discoloration spreads upward.
- Bacteria initially causes abdominal bloating by producing gas, which is first seen in the face.
- Decomposition fluids (not blood) often have a pinkish appearance and exit through the nose and mouth.
Order of Changes
- First sign: Green discoloration in the lower abdomen.
- Sulph-Hb staining of superficial veins (marbling).
- Skin slippage
- Skin blisters form and are filled with dusky fluid and gases.
- The blisters burst with slight contact.
- Gas formation increases in the abdomen, causing swelling. - Methane, H₂S, Ammonia, CO₂
- Swollen face and limbs.
- The eyes and tongue become protruded.
Adipocere
- Also known as grave wax, a waxy substance formed from the breakdown of fats.
- Forms on body parts with high fat content (cheeks, breasts, abdomen, buttocks).
- It forms when fats in the body reacts with water and hydrogen in the presence of bacterial enzymes to form fatty acids and soaps.
- The process takes weeks or months.
Adipocere (Saponification)
- Characterized by yellowish-white, greasy, wax-like substance.
- Has a sweetish rancid odor.
- Remains unchanged for years in specific conditions.
- Formation facilitated by warm, moist environments; reduced with high levels of drying.
- Released fatty acids inhibit bacterial growth.
Skeletonization
- Body becomes a skeleton form through the loss of soft tissues.
- The rate of this process varies greatly based on environmental and biological factors.
- Insects and wildlife play a role.
Mummification
- Body dehydration or desiccation results in a leathery or parchment-like mass.
- Occurs in dry environments (Deserts, Cabinets).
- Internal organs may, or may not, remain preserved.
- Skin shrinkage may form splits that mimic injuries.
Forensic Entomology
- Study of arthropods (insects) associated with a corpse to estimate the time since death.
- Blowflies and bluebottles (Calliphoridae) are important insects in the process of decomposition.
- Their development stages are studied to establish a time since death estimation.
Life Cycle of a Typical Blowfly
- Stages involve eggs, larva stages (1st, 2nd, 3rd), pupa, and adult stage.
- Development time varies based on temperature conditions.
Larval Stages in Blowfly Life Cycle
- Different larval instars.
- Time duration for each larval instar.
Insect Succession
- Insects colonize a deceased body in a predictable sequence.
- Corpse is a rich food source for insects for a limited time.
Stages of Decomposition
- Fresh: Initial stage; blowflies and flesh flies lay eggs.
- Bloated: Corpse swells due to gas formation from decomposing bacteria.
- Decay: Large amounts of maggots.
- Post-decay: Body drying; fewer flies, more beetles.
- Dry: Skin and bones remain.
Caveat!
- Insect succession varies by climate.
- Indigenous species knowledge is essential when estimating the time since death.
Methods
- Old rule of thumb: 1°C per hour to estimate cooling.
- Nomogram method (using Henssge Nomogram) is best researched and documented methodology -Requires rectal temperature. -Uses corrections for multiple factors.
Nomogram Method
- Nomogram method involves factors like body weight, ambient temperature, clothing conditions (dry/wet) and if there is water movement (still or flowing).
- More precise with use of multiple correction factors. -Corrects for variation from standard based conditions.
Other Methods for TSD Estimation
- Stomach contents emptying: Time since consumption determines the time since death. -Light meal: 2 hours. -Heavy meal: 4-6 hours.
- Factors influencing estimation include the type of food, metabolic rate, drugs, alcohol, and exercise.
Plant Evidence in the Stomach
- Estimates of time since death are based on average digestion times of food.
- Mouth: <2 minutes.
- Stomach: 2–6 hours.
- Small intestine: 2–8 hours.
- Large intestine: 6–9 hours.
- Total: 10-25 hours.
Was McDonald the last meal?
- A case study where a woman's stomach contents (McDonald's items) was used to estimate time since death.
Black Widow
- A criminal case that used stomach contents analysis to help determine time since death.
Ancient Remains
- Grauballe Man's stomach contents revealed details about the last meal and clues about the time since death.
Vitreous Humour Chemistry
- Vitreous humor is stable, no contamination or fast chemical changes.
- The vitreous humor is unaffected by environmental factors, and is sampled from the eye to estimate the time of death.
- Potassium concentration in vitreous humor increases linearly over time after death.
- There are several calculations and differences in opinions on how to estimate time since death based on potassium concentration.
Vitreous Humour
- Accuracy relies on correct sampling method used.
- Aspiration near the retina will distort the value.
- Accuracy is lessened with chronic illnesses.
- PMI +/- 6-12 hours in a 95% confidence limit.
- Most popular calculation formula: PMI = 7.14 x Potassium concentration (mEq/l) - 39.1.
- More accurate for bodies that have been at temperatures below 10 degrees.
Activity
- Groups can research papers on post mortem interval methods based on their specific parameters in order to estimate the time of death.
- Students should note down all results and limitations.
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Description
Test your knowledge on the processes of decomposition and mummification with this quiz. Dive into the characteristics associated with mummification, signs of decomposition, and the environmental factors influencing these processes. Discover how various factors contribute to the transformation of body tissues after death.
