Forensic science quiz #2

Forensic Taphonomy:

the study of the history of the body since death. Taphos meaning burial or grave. Nomos meaning laws. It deals with the changes in the body/body parts In medical and legal cases

TAPHONOMIC FACTORS

1. Environment 2. Activities of living beings - organisms 3. Animals, plants, etc

Why is taphonomy important?

+ Identify clandestine graves / deliberate burials

TAPHONOMIC TECHNIQUES

• Three-dimensional mapping • Botanical and Entomological collections procedures • Conservation and exhumation techniques • Computerized mapping

TWO BRANCES OF FORENSIC TAPHONOMY

1. BIOTAPHONOMY • Examines the remains • Regards to their decomposition and destruction 2. GEOTAPHONOMY • Study of how someone who buries a body • How the body itself affects the surrounding geological and botanical environment

FORENSIC TAPHONOMIC MODEL (Four dimensions:)

1. Objects: are human remains 2. Space: environment 3. Modifications of the object: by physical or biological factors 4. Cultural dimensions: affects the fate of the human remains

TIMES OF DEATH:

(1) Ante mortem: prior to death (2) Perimortem: at the time of death (3) Postmortem: Time period after death

TAPHONOMIC PROCESSES:

Temporal components:

Perimortem interval

How much time was passed during this time; Of particular interest in medical legal death investigation if person died; Time frame that includes death.

Perimortem interval also includes:

The boundary between soft tissue modification and bone exposure, Interval in which bone is exposed to modifying agents (weather, water, soil, animals, etc)

Ante mortem injuries:

Characterized by healing; Include ability to define moisture and grease content of bone such as greenstick or spiral fractures

Postmortem fractures

Include clean brittle breaks, parallel or cross fracture of long axis of bones; Moisture loss occurs over time

Postmortem interval:

How much time has lapsed since the person is dead; Estimating can be as imprecise as estimates of peri mortem interval; Observations from death to recovery has to be specified by forensic scientists e.g When remains were found vs when it occurred

Certain postmortem processes lend themselves to partitioning including;

Decomposition; Carnivore disarticulation; Weathering

Several factors affect estimates of postmortem interval:

Determining triggering event; Rate of change; Cultural and environmental factors; Carcass temp and loss of blood; Atmospheric conditions; Location of deposition of body - water, underground, on top of ground

ANIMAL ASPECTS OF HUMAN REMAINS:

Insects are important in being able to determine date of death (T/F)

TRUE

Two major orders of insects:

(1) Diptera (flies) (2) Coleoptera (beetles)

Characteristics of both insects:

Both are noted to assist in estimating time of death of a person (corpse) e.g Because each of these insects will attack the corpse at a particular time in death; Life cycles of flies can be determined by specific stage of egg, maggot or pupae; Beetles normally feed on fly eggs and larvae, but may feed on carrion (body); Estimates of insect development are affected by context of and environment in which the corpse is found; use 75% ethyl or 50% isopropyl alcohol as preservative

Species succession:

Later other insect species arrive at the carcass. The community profile is used to estimate time since death

Succession impact:

Influenced by geographical regions, habitat, seasons etc

Dogs and rodents are primary scavengers of remains (T/F)

True

Dogs and cats leave v shaped defects in soft tissue

TRUE

Clawing digging or tugging at remains can also alter appearance

TRUE

Rodents leave tightly circumscribed and even margins

TRUE

Scavengers also leave behind hair

tracks and feces , TRUE

PLANT ASPECTS OF HUMAN REMAINS:

Seasonal shedding of leaves or needles can cover remains; Roots can cause mechanical damage; Fungi can secrete acid; Micro environmental changes can be caused by rootlet proximity to bones and subsequent moisture conservation and microbial activity

DECOMPOSITION:

Chemistry of living cells is characteristically:

At around 37 degrees C; Aqueous (as cells are mostly water); Highly catalyzed (by enzymes); Well segregated by lipid bound membranes and organelles

Decomp In death:

Decomposing body remains for a time a dynamic state

Following death:

Manner of disposition affects rate of decomp

Physical and chemical factors:

Temp; Water; Acidity and alkalinity; Partial pressure of oxygen; Autolysis (cells eating themselves) and cell death

POST MORTEM PHENOMENA:

Rigor mortis:

Stiffening of muscle because ATP is loss

Water presents a myriad of problems with death investigators; why?:

Type of water body are all diff ;Disarticulation in water and problems with original location of water; Temp, depth, and current of water all affect body decomp as does seasonal weather

DNA RECOVERY IN POSTMORTEM SAMPLES:

To determine individual identity; Preservation of DNA in non living samples; Nuclear DNA; Mitochondrial DNA