Death Investigation

Forensic Medi: The application of medical specialties to legal issues.

Medical Professionals

• Forensic pathologist – medical doctor who studies injuries and disease to determine the cause of death

• Coroner – elected official who oversees a death investigation

• Medical examiner – forensic pathologist who completes autopsies and determines the cause and manner of death

Death Investigation

Three questions need to be answered:

1. Cause of death – relates to the disease or injury that actually brought about death

2. Mechanism of death – the biologic or physiologic means of death

3. Manner of death – refers to the intent or series of events that brought about death

5 Manners of Death

• Natural

• Accidental

• Homicide

• Suicide

• Undetermined/unknown

Active Unidentified Missing Persons Cases

Autopsy: Usually only completed for unexplained or suspicious deaths

External Examination:

• Overall health is observed

• Height, weight, and physical characteristics are noted

• Injuries are documented

• The body is X-rayed

• Fingernails are scraped

• Fingerprints are collected

• Trace evidence on the body is documented, collected and preserved

Internal Examination

• Organs are examined, weighed and measured

• Tissue samples are microscopically examined

• Fluid samples are sent to a toxicologist

*all items collected during autopsy must be preserved and properly stored (chain of custody)

What Happens to the Body at Death

1. Algor Mortis

   • temperature drops at a regular rate

2. Rigor Mortis

   • The body stiffens as a result of the lack of oxygen and ATP

   • Begins 4 hours after death

   • Starts in the face and digits and spreads through the rest of the body

   • Is complete within 12 hours

   • The body returns to a non-rigid state after 30 -36 hours

3. Livor Mortis (a.k.a. “lividity”)

   • Discoloration of the skin caused by the settling of blood

   • Occurs in the part(s) of the body lying closest to the ground

   • Becomes fixed after 6-8 hours

5 Stages of Decomposition

1. The “Fresh” Stage (days 1-2)

   • Begins 4 minutes after death

   • Autolysis (self-digestion) occurs as the poisons inside cells build up

   • Algor, livor, and rigor mortis occur

2. The “Bloated” Stage (days 2-6)

   • After cells rupture, putrefaction occurs

   • Bacteria produce gases while feeding off the body’s fluids

   • Body swells up and may look greenish in color

   • Body temperature will spike upwards

3. The “Active Decay” Stage (days 7-23)

   • Skin breaks open and the gases escape

   • The body emits a very strong, foul odor

   • Body loses most of mass as microbes and insects consume the soft tissues

4. The “Advanced Decay” Stage (3 weeks – 2 months)

   • Remaining tissues are broken down

   • Speed of decomposition slows

   • Plants around corpse die, but fungi flourish

5. The “Skeletal” Stage (2+ months)

   • Skeletonization leaves just bones and hair

   • Diagenesis eventually occurs, breaking down bone

Factors Affecting Decomposition:

• temperature

• moisture levels

• location of the body (fully exposed, buried, underwater)

• injuries on the body

• presence of carnivores and insects

Specialized Decay Processes

• Saponification - formation of soap from fat (high pH in warm, moist environments)

• Mummification - skin is converted to a leathery sheet

• Hot, dry environments

• Frozen environments

• Bogs

Body Farms in the U.S.

University of Tennessee at Knoxville

Western Carolina University

Texas State University

Sam Houston State University

Southern Illinois University

Colorado Mesa University

University of South Florida

Forensic Entomology

The use of insects that inhabit decomposing remains to aid legal investigations.

The Job of a Forensic Entomologist:

1. Identify insects at various stages of their life cycle

2. Collect and preserve insects as evidence

3. Determine an estimate for the postmortem interval or PMI (the time between death and discovery of the body)

Insect Life Cycle

Most forensically important insects undergo complete metamorphosis

eggs → larva → pupa → adult

Types of Carrion Insects

1. Necrophagous species

   • feed directly on the corpse

   • blow fly and flesh fly are most common

   • can arrive as quickly as 10 minutes after death

   • females feed off body fluids and lay eggs in body cavities

2. Predators and parasites

   • Predators are insects that hunt and eat other insects

   • Ex. Beetles prey on eggs and larvae (maggots) of flies

   • Parasites rely upon insects in other ways

   • Ants, bees, and wasps lay their eggs inside or on top of the larvae

3. Omnivorous Insects

   • Some types of wasps, beetles and ants feed on both the corpse and on other insects

4. Normal Insects

   • Insects that already inhabit the area where the body was deposited

   • Ex. Hunting spiders weave webs over body parts

   • Ex. Soil-dwellers feed off body fluids that have seeped into the surrounding soil

• Insects and the Stages of Decay

1. Fresh stage – necrophagous flies lay eggs that hatch (maggots)

2. Bloated stage – predators and parasites arrive, laying more eggs = more maggots

3. Active Decay stage – number and type of insects increases; beetles consume flesh

4. Advanced Decay stage – different types of beetles show up; mites inhabit the soil under the body

5. Skeletal stage – no more insects except ones that normally live in the area

Forensic Anthropology

Forensic anthropologists specialize in recovering and examining human skeletal remains from unexplained deaths.

Job of Forensic Anthropologist

• determine age, sex, height, ancestry, and some behaviors of individuals from their skeletal remains

• work with the medical examiner to determine the cause of death

• work with entomologists to determine PMI (postmortem interval)

Questions asked by a forensic anthropologist when profiling skeletal remains:

1. Are the remains human?

   • Bone cells – human are round

   • Ribs – human are C-shaped, have 12 or less pairs

   • Limbs – children (when compared to animals) have unfused epiphyses

   • Limbs – human bones are usually smoother, longer, and thinner than most animals

2. How many individuals are represented by these bones?

   • Duplication of bones

   • DNA analysis

   • Differences in age, size, & preservation of bones

3. What was the sex of the individual?

   • Male skeletons are generally larger

   • Can compare the pelvic bones:

   • Female – wider, smoother, lighter

   • Male – narrow pubic arch and sacrum

4. What was the age of the individual

   • Easy to determine in infants and children

   • length of bones, amount of cartilage

   • Adults are more difficult

   • bones become rougher, osteoporosis and arthritis are more likely, and teeth show more wear as you age

   • Lambdoid – 30 years

   • Sagittal – 31-32 years

   • Coronal – 50 years

5. What was the ancestry of the individual?

   • Skull features and teeth can be used for comparison

   • There are 3 general ancestral categories: European, Sub-Saharan African, Asian/American Indian

6. What size was the individual?

   • Anthropometry uses the lengths of bones to determine a person’s height

   • Different calculations are used for each type of long bone.

A. Bertillon

• Founder of anthropometry

• Created his own filing system based on 9 measurements

• Also known for crime scene photography & as the inventor of the mugshot

Odontology: The application of dental science to problems of human identification.

Job of Forensic Odontologist

1. Identifying unknown remains.

   • Take dental x-rays during autopsies

   • Compare dental x-rays with dental records

2. Analyzing bite marks on evidence related to a crime.

3. Criminals can bite victims during violent crimes

4. Victims can bite suspects in self-defense

5. Both victims & suspects can leave bite marks impressed in foods