Transcript File - Ms. Collins forensic science

WARM-UP

During a recent police investigation, Chief Inspector Stone was
interviewing five local villains to try and identify who stole Mrs
Archer's cake from the mid-summer fair. Below is a summary of
their statements:
Arnold: it wasn't Edward
it was Brian
Brian: it wasn't Charlie
it wasn't Edward
Charlie: it was Edward
it wasn't Arnold
Derek: it was Charlie
it was Brian
Edward: it was Derek
it wasn't Arnold

It was well known that each suspect told exactly one lie. Can you
determine who stole the cake?
1
FORENSIC TAPHONOMY
FORENSIC TAPHONOMY

Forensic taphonomy is the study of the history of the
body since death.

Taphonomy is derived from Greek taphos (burial) and
nomos (laws).

Taphonomy is important because it may assist in;

Estimating the time since death by observing postmortem
changes

Identification of the individual

Ability to determine cause and manner of death
CATEGORIES OF TRAUMA
1.
2.
3.
4.

Mechanical – sharp or
blunt
Thermal –
hyperthermia or
hypothermia
Chemical – drgus or
poisins, CO kills by
asphxyation
Electrical – causes
ventricular fibrilation
Asphyxial – low Oxygen
Eccymosis
Ligature Marks
Petechia
5
MECHANICAL
Sharp

Knives, Swords, Axes
Blunt

Firearms
Handgun
 Shotgun


Nonfirearms
6
Blunt force
Hesitation
7
Double edge
Slash
wound
Single edge
8
ENTRANCE WOUNDS

Close
Contact wound – skin blackens
 Red discoloration due to released CO (few inches)
 Larger lacerations on head wounds


Intermediate
Less gas effects
 Stippling/tattooing from unburned powder


Distance
Circular defect
 Abraded rim on skin

9
Shotgun Close
Contact Wound
Intermediate
Close Handgun
10
Distance wound
Intermediate –
Stippling/tattooing
11
EXIT WOUNDS
Not always larger
 Small slit shaped
 Slow speed - few side lacerations
 High speed – many side lacerations “bunny ears”
 Shored exit – due to clothes, easily confused with
distance entrance but abrasions are wider than
entrance

12
With lacerations
Shored exit versus entrance
wound
Without
laceratio
ns
13
TRAUMA TERMS TO KNOW
Hematoma – “goose eggs”, tumor of blood
 Contusion – leaves patten of weapon when blood
leaks out of cells
 Laceration – blunt force wound
 Incised wound – sharp force wound
 Stab – longer length than width wound
 Exsanguination- bleed out
 Perforating – gun wound with entrance and exit
 Penetrating – gun wound with no exit

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WHAT IS FORENSIC TAPHONOMY
 Taphonomy
is the study of the processes
that affect the decomposition, dispersal,
erosion, burial, and re-exposure of
organisms after, at, and even before
death.
 Forensic Taphonomy is a subfield of
forensic anthropology.
BIOTAPHONOMY
Biotaphonomy examines the remains themselves
and asks how decomposition and destruction of
the hard and soft tissue was brought about.
 Biotaphonomic variables can be subdivided

Environmental factors
 Individual factors
 Cultural factors

GEOTAPHONOMY

Geotaphonomy is the study of how someone who
buries a body, and how the body itself affects the
surrounding geological and botanical
environment.
CONTRIBUTIONS OF METHODS
AND THEORY


Forensic taphonomy requires interdisciplinary
input from biologists, archeologists,
anthropologists, entomologists, botanists and
geologists, among others.
Forensic anthropologists are primary facilitators
of taphonomy into forensics
CONTRIBUTIONS OF METHODS
AND THEORY
Archaeological techniques of recognition, search,
recovery, and documentation of findings are
critical in taphonomy
 Other techniques, such as 3-D mapping,
stratigraphy, botanical and entomological
collection, conservation, and exhumation are
used.

TAPHONOMIC FACTORS

Forensic Taphonomic history includes:
Actual death
 Interval of bone exposure through soft tissue
modification
 Potential interval of bone modification
 Point of discovery and collection

TAPHONOMIC FACTORS

Of particular interest in medicolegal death
investigation is:
Perimortem interval,
 Boundary between soft tissue modification and bone
exposure,
 Interval in which bone is exposed to modifying agents
(weather, water, soil, animals, etc)

TAPHONOMIC FACTORS
 Perimortem
interval- discriminating
antimortem from postmortem injuries to
bone is difficult
 Antimortem/Perimortem injuries include
ability to define moisture and grease
content of bone, i.e.; greenstick, or spiral
fractures
 Postmortem fractures include clean brittle
breaks, parallel or cross fracture of long
axis of bones
 Moisture loss occurs over time
TAPHONOMIC FACTORS

Several factors affect estimates of postmortem
interval:






Determining triggering event
Cultural factors
Environmental factors
Carcass temperature and loss of blood
Atmospheric conditions
Location of deposition of body – water, underground,
on top of ground
TAPHONOMIC FACTORS


Animals and human remains
Most commonly found scavengers of human
remains are:
Carnivores
Rodents
Insects
Microbes

TAPHONOMIC FACTORS
 Dogs
and rodents are primary scavengers
of remains

Dogs and cats leave v-shaped defects in soft
tissue
 Clawing,
digging or tugging at remains
can also alter appearance

Rodents leave tightly circumscribed and
even margins, dual teeth marks
 Scavengers
and feces
also leave behind hair, tracks
TAPHONOMIC FACTORS

Plants and human remains:
Seasonal shedding of leaves or needles can cover
remains
 Roots can cause mechanical damage
 Fungi can secrete acid
 Microenvironmental changes can be caused by rootlet
proximity to bones and subsequent moisture
conservation and microbial activity

HUMAN REMAINS IN WATER
ENVIRONMENTS

Water presents a myriad of problems with death
investigations:
Type of water body (ocean, river, lake)
 Disarticulation in water and problems with original
location of water
 Temperature, depth, and current of water all affect
body decomposition, as does seasonal weather

BURIED REMAINS
 Major
problem by burial is locating grave
 Methods to determine grave location
include:






Witness statements
Visual clues
Cadaver dogs
Trenching and probing
Area photography
Remote sensing
BURIED REMAINS

Buried bodies normally decompose slower than
bodies on surface due to:






Less exposure to scavengers and insects
Temperature fluctuates less the deeper the body is in
grave
Less exposure to weather
Compaction of soil
Differences in pH due to decaying matter
Moisture level
The Body Farm
The research farm, known
as The Body Farm, was
established in 1981 by Bill
Bass, a professor of
forensic anthropology.
http://video.nationalgeographic.com/
video/player/science/health-humanbody-sci/human-body/body-farmsci.html
THE BODY FARM



PRIMARY GOAL: To understand the processes &
timetable of postmortem decay, primarily to improve
determining the "time since death”
The Body Farm is a simulation of various crime scenes
using real human bodies.
Started in 1970-80’s to study Forensic Anthropology
(the study of human decomposition after death).
THE BODY FARM
 Used
by Law Enforcement, Medical
Examiners, Entomologists, Cadaver Dogs,
Anthropologists & FBI for Crime Scene
Training.
 The BF uses unclaimed cadavers & volunteers
(who donate their body to science after death)
 Only 2 Facilities in the U.S.




Univ. of Tennessee (original)
Western Carolina University
Texas State University
Sam Houston State University
TYPES OF RESEARCH
How does the decomp rate compare in:






sunshine vs shade?
In cool weather vs hot weather?
In a shallow grave vs on the ground?
In water?
Inside a car?
What effect do other variables have—humidity,
insect activity, clothing, body weight, and so on?
WHY IS TSD SO IMPORTANT?


1st question at most murder scenes: "How long
has this person been dead?“
It's crucial to know when the crime was
committed.
it can help narrow the search for a suspect or
 it can help rule out potential suspects who had alibis
at the time the victim was killed.
