forensics autopsies test

postmortem interval (pmi)

time between death and discovery of the body. Estimated using insect evidence, weather data, and the body's condition.

sequential steps performed during an autopsy

External exam and collect evidence

Photograph/X-ray/weigh body

Clean and position body

Make Y-incision and examine organs

purpose of a "Y" incision made during an autopsy

cut from shoulders to sternum and down midline

remove rib cage

examine chest and abdomen organs

examine brain by removing scalp/skull

insects attracted to body during late stage decomposition

- ham and checkered beetles-- predator of flies & beetles; also feed on dead tissue

- skin beetles-- feed on dried skin and tissues

- hide beetles-- usually the last to arrive

A forensic entomologist's job may include

- Identification of insects at various stages of their life cycle, such as eggs, larva, and adults.

- Collection and preservation of insects as evidence.

- Determining an estimate for the Postmortem Interval or PMI (the time between death and the discovery of the body)

- Use the following factors:

- insect evidence

- weather conditions,

- location and condition of the body, etc.

- Testifying in court to explain insect-related evidence found at a crime scene.

Investigators will make note of the temperature of the...

- Air

- ground surface

- the interface area between the body and the ground

- the soil under the body

- the temperature inside any maggot masses.

algor mortis

the cooling of the body after death

livor mortis

blood settling in the lower parts of the body after death, causing discoloration

rigor mortis

What it is: The stiffening of muscles after death.

Cause: Chemical changes in muscle tissue (specifically ATP depletion).

Time Frame: Begins ~2-6 hours after death and can last up to 72 hours.

incised wound

a cut made by a sharp object like a knife

hesitation marks

small shallow cuts made before a deeper self-inflicted wound

factors that affect the onset of rigor

temperature, body size, illness, physical activity before death

stages of decomposition

fresh, bloat, active decay, advanced decay, dry remains

Insects arrive at the body within _____ of death if the body is exposed

minutes, as little as 10

how are insects helpful

they help estimate time of death

insects typically first to arrive at a body

blowflies

Sequential steps in insect development

egg, 1st 2nd and 3rd instar larva (maggot), pupa, adult

most bizarre stages of external tissue decay

bloat and active decay

A bone is found with lacy cracking on the surface. What does this mean?

weathering and long exposure after death

As insect larva grow they generally ____________ in length which helps entomologists determine the larva's age:

increase

Length of the life cycle varies between species and is dependent on what

temperature/environment

Compare a coronial autopsy to a hospital autopsy (why, where, can anyone stop them from happening)

coronial- ordered by law for suspicious/unexplained deaths; family usually cannot stop it

hospital- done for medical reasons or learning; family can refuse it

Where is the incision made to remove the brain and what is done with the brain after the incision

incision is made behind/around the scalp from ear to ear; brain is removed and examined

Difference between cause of death and mechanism of death, and examples

cause-- the injury or disease that killed the person (ex: gunshot wound)

mechanism-- how the body failed because of it (ex: blood less)

example of a situation where a post mortem injury can look like an anti mortem injury

animal bites or body damage after death may look like bruises or wounds from before death

forensic entomology definition

The application of insect science to legal investigations, particularly to determine time since death (Postmortem Interval or PMI). Combines insect study with forensic investigations.

Used in postmortem analysis to:

Estimate time of death based on insect life stages.

Detect presence of drugs or toxins (through insect larvae).

Understand the location and condition of body over time.

Insect Orders Used in Investigations-- Diptera (Flies)

Includes blowflies, flesh flies, and house flies.

Insect Orders Used in Investigations-- Coleoptera (Beetles)

Includes carrion beetles, hide beetles, and rove beetles.

Blowfly Life Cycle (Approximate Timeline)

1. Eggs (<24 hrs after death): Laid near body openings or wounds.

2. Larval Stages (Maggots):

1st Instar: Day 1-2.5

2nd Instar: Day 2.5-4

3rd Instar: Day 4-8 — larvae feed actively, then migrate to dry areas.

3. Pupal Stage:

Early Pupa: Day 8-18

Late Pupa: Day 18-24

4. Adult Fly Emerges: Around Day 24+

Environmental Factors Affecting PMI-- temperature

Air, soil, and maggot mass temperatures are recorded.

Weather Data

Historical highs/lows and precipitation help estimate development speed.

Barriers

Wrapping or enclosing a body delays insect colonization.

Maggots as Evidence

- Can reveal presence of drugs or toxins, which may speed up or slow down development.

Useful when tissue samples are decomposed beyond testing

Stage of Decomposition and Insects Present in Fresh

Blowflies, fresh flies, yellow jackets.

Stage of Decomposition and Insects Present in bloat

Blowflies, beetles, maggots.

Stage of Decomposition and Insects Present in active decay

Flies, beetles, cockroaches.

Stage of Decomposition and Insects Present in advanced decay

Beetles, gnats, fruit flies.

Stage of Decomposition and Insects Present in dry

Beetles, ants, spiders.

Carrion Beetles (Silphidae

Feed on maggots.

Clown Beetles (Histeridae)

Feed on eggs and larvae.

Hide Beetles (Scarabidae)

Arrive last, feed on dried tissue.

Rove Beetles (Staphylinidae)

Early predators of fly eggs.

Body Farm

A real-world facility in Knoxville, Tennessee used to study human decomposition under varying conditions.

Helps develop more accurate PMI estimation methods.

Antemortem

Before death

External Examination

Injuries, marks, or clues on the outside of the body.

autopsies are Performed by:

A Forensic Pathologist.

Main Purposes of an autopsy:

Determine cause of death (how someone died).

Determine manner of death (e.g., homicide, suicide, accidental, natural, undetermined).

Assist in legal investigations (especially in suspicious or unexplained deaths).

autopsy definition

A detailed medical examination of a body after death.

Decomposition

Described as the "smelly science" due to gases and fluids released.

Helps estimate time since death and evaluate environmental effects.

Involves bacterial activity, insect activity, and breakdown of tissues.

Mathieu Orfila

Known as the Father of Forensic Toxicology. He pioneered techniques for detecting poisons and studying their effects on the human body.

Internal examination

Organs are inspected for damage or disease.

Toxicology Tests

Check for drugs, poisons, or alcohol in the body.

Documentation

All findings are recorded in an autopsy report.

Perimortem

Around or near the time of death

Postmortem

After death

Forensic Toxicology:

Identifies drugs, poisons, and toxins in the body.

Determines the cause-and-effect relationship between substance exposure and toxic or lethal outcomes.

Types of Toxic Substance Exposure-- intentional

Therapeutic use (e.g., pain relief).

Types of Toxic Substance Exposure-- Accidental

Overdoses, harmful drug combinations.

Types of Toxic Substance Exposure-- Deliberate

To harm, kill, or commit suicide.

Poison & Drug Offenses

Poisoning causes less than 0.5% of homicides.

Accidental drug overdoses are far more common.

Drug offenders make up:

Over 50% of the federal prison population.

About 20% of state prison populations.

Categories of Controlled Substances (category, effect/use): hallucinogens

Alter perception, thinking, emotions (e.g., LSD, psilocybin).

Categories of Controlled Substances (category, effect/use): narcotics

Suppress pain and central nervous system (e.g., morphine, heroin).

Categories of Controlled Substances (category, effect/use): stimulants

Increase energy, alertness; highly addictive (e.g., cocaine, amphetamines).

Categories of Controlled Substances (category, effect/use): anabolic steroids

Enhance muscle growth; mimic testosterone.

Categories of Controlled Substances (category, effect/use): depressants

Slow down brain activity, increase GABA activity (e.g., barbiturates, Xanax).

Effects of Drugs

Stimulants

Boost alertness, suppress appetite; can lead to seizures and depression.

Effects of Drugs

Depressants:

Cause drowsiness, slurred speech, poor coordination. Dangerously intensified when mixed with alcohol.

Effects of Drugs

Anabolic Steroids: :

Promote tissue/muscle growth but can have harmful side effects (e.g., hormonal imbalances).

Effects of Drugs

Hallucinogens:

Overdose: high heart rate, psychosis, panic attacks.

bacterial toxin tetanus effect

Causes severe muscle spasms (lockjaw).

bacterial toxin botulism effect

Causes paralysis; most poisonous biological toxin.

Bioterrorism Agents ricin

Extracted from castor beans.

Enters the body via inhalation, ingestion, or injection.

Lethal in tiny doses, causes death within hours.

Bioterrorism Agents Anthrax

Caused by Bacillus anthracis spores.

Enters the body through:

Inhalation (most deadly)

Ingestion

Skin absorption