Transcript Presentation

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• FORENSIC SCIENCE
• Is an applied science
–Pure science seeks to
understand the physical
world for its own sake.
–Applied science seeks to
use physical principles to
obtain a desired goal.
* Remember *
Science is Dynamic
• At any point in time, science
gives our best estimate of
how the universe works.
• New discoveries may refine
or refute what was
considered to be “true”.
• Understanding changes with
new information. Examples –
• Landmarks of Forensic
Science
• 1149 – Position of Coroner
started by King Richard of
England.
• 1590 – Microscope developed
by Zacharias Janssen of
Holland.
• 1670 – First powerful
microscope created by Anton
Van Leeuwenhoek.
• 1732 Luigi Galvani discovered
human nervous system
transmits information
electronically (lie detector)
• 1807 – Forensic Science
Institute opened at the
University of Edinburg,
Scotland.
• 1823 – Whorls, ellipses, and
triangles identified by Jan
Evangelista Purkinjie.
• 1836 – Method for detection
of arsenic poison developed
by Marsh of England.
• 1850 – First private
detective agency set up by
Allen Pinkerton.
• 1859 – Spectroscopy was
developed by Kirchoff and
Bunson.
• 1880 – Sherlock Holmes
detective stories published
by Sir Arthur Conan Doyle.
• 1888 – Hand held camera
invented by George Eastman.
• 1889 – Bullets are matched
to the gun they were fired
from.
• 1892 – Scientific
classification of fingerprints
developed by Galton.
• 1895 – X-rays discovered.
• 1896 – System of matching
fingerprints to identify
people developed by Ed
Henry.
• 1901 – Human blood groups
identified.
• 1903 – NYC police begin
fingerprint files of arrested
persons.
• 1909 – Chromosomes
discovered to carry
hereditary information.
• 1910 – First forensic
laboratory opened in France
by Edmond Locard.
• 1930 – National fingerprint
file set up by FBI.
• 1932 – FBI forensic
laboratory established.
• 1980 – Method for detecting
DNA differences developed.
• 1987 – First time DNA
evidence is used to convict a
person in U.S.
• BASIC SERVICES PROVIDED
BY A CRIME LABORATORY
• Physical Science Unit –
Applies principles and
techniques of chemistry,
physics, and geology to the
identification and comparison
of crime scene evidence.
• Biology Unit – staffed with
biologist and biochemist who
apply their knowledge to the
identification and DNA
profiling of dried blood and
other body fluids, and the
comparison of hairs and
fibers.
• They also compare and
identify botanical materials
such as wood and plants.
• Firearms Unit – conducts the
examination of firearms,
discharged bullets, cartridge
cases, shotgun shells, and
ammunition of all types.
Clothing and other objects
are also examined for
residue and to approximate
the distance from the fired
weapon.
• Document Examination Unit –
Study handwriting and
typewriting to determine
authenticity and/or source.
Analysis of inks, paper,
erasures, and burned or
charred documents.
• Photography Unit – Uses
digital imaging, infrared,
ultraviolet and X-ray
photography to make invisible
evidence visible. Also help
prepare photographs for
courtroom presentations.
`
Voice Analysis Unit –Analyzes
tapes and recordings,
voiceprints.
Evidence Collection Unit –
Dispatches specially trained
personnel to the crime scene
to collect and preserve
evidence.
The Functions of the Forensic
Scientist
1. Analysis of Physical
Evidence.
The procedures and
techniques used in the lab
must have a firm
scientific foundation.
• They must also be
acceptable to the court. In
the case Frye v. United
States the courts said for a
procedure, principle, or
technique to be admissible it
must be generally accepted
by the scientific community.
• In the 1993 case Daubert v.
Merrell Dow Pharmaceutical,
Inc. Supreme Court ruled
that judges where to be
“gatekeepers” in deciding the
admissibility of scientific
evidence and testimony.
• The guidelines judges use to
determine admissibility are
• A. Has the technique or
theory been tested?
• B. Has the technique or
theory been subject to peer
review and publication?
• C. What is the potential
rate of error?
• D. Have standards been
applied to the technique?
• E. Has the theory or method
been widely accepted by the
scientific community?
2. Provide Expert Testimony
Because their work may
ultimately be used to
determine a persons guilt or
innocence, a forensic
scientist may be required to
testify in court about their
methods and conclusions.
• The courts take several
things into consideration
when deciding if a person is
an expert. These may
include questions,
presentation of degrees or
certificates, years of
experience, or publication.
• Both sides should agree to
call a person an expert
witness but the judge has
final determination.
• 3 Furnish training in the
proper recognition,
collection, and preservation
of physical evidence.
• Some other fields in forensic
science include:
–Forensic Pathology
–Forensic Anthropology
–Forensic Entomology
–Forensic Psychiatry
–Forensic Odontology
–Forensic Engineering
• FORENSIC PATHOLOGY
• 1. Involves the investigation
of sudden, unnatural,
unexplained, or violent
deaths.
• 2. The major question to be
answered is What caused the
death?
• 3. Sometimes the cause of
death may be apparent,
sometimes an autopsy may be
required. An autopsy is the
medical dissection and
examination of a body in
order to determine the cause
of death.
• http://www.nlm.nih.gov/visibl
eproofs/galleries/media/index
.html
• There are five categories
that a death may fall into
–Natural
–Homicide
–Suicide
–Accident
–Undetermined
• 5. Decomposition process and
time of death.
• A. Immediately following
death the muscles relax and
then become rigid. This is
called rigor mortis. It usually
begins within 24 hours and
disappears in about 36
hours.
• B. Livor mortis is another
useful tool in determining
time of death. When the
heart stops pumping blood it
begins to settle in the areas
closest to the ground due to
gravity.
• The skin in this area will
become darker. This begins
immediately after death and
continues for up to twelve
hours after death. Livor
mortis is useful in
determining if a body has
been moved or changed
position after death.
• C. Other chemical and
physical changes that occur
after death may be useful in
determining time of death.
Algor mortis is the process
in which the body loses heat
after death until it reaches
the same temperature as its
surroundings.
• The rate at which a body
loses heat is determined by
many factors such as the
amount and type of clothing,
weather conditions, and the
size of the body. A body
placed in water loses heat
much faster than one on or
above the ground.
• As a general rule, beginning
an hour after death the
body loses heat at a rate of
approximately 1 to 1½
degrees per hour until the
environmental temperature is
reached.
• D. Another way to estimate
the time of death is by
determining the potassium
levels in the fluid of the eye
(vitreous humor).
• FORENSIC ANTHROPOLOGY
–Concerned primarily with
the identification and
examination of human
skeletal remains. Because
bones are so durable they
can be used for a long time
after death.
• From the study of skeletal
remains we can determine
characteristics such as age,
height, sex, race, physical
condition and appearance.
• Some specialize in facial
reconstruction to aid in
identification. Forensic
anthropologist also identify
victims of mass disasters by
using bones collected from
the scene.
• Forensic Psychiatry
–A specialized area in which
the relationship between
human behavior and legal
proceedings is evaluated.
• In criminal cases forensic
psychiatrist evaluate
behavioral disorders and help
the courts determine if a
person is competent enough
to stand trial. They also
examine behavioral patterns
of criminals in order to
develop a behavioral pattern.
• Forensic odontology
–They provide information
about the identification of
bodies in unrecognizable
states. Teeth are made of
enamel which is the hardest
substance found in the
body.
• They usually survive. Dental
remains can be identified by
using dental records such as
x-rays, dental castings, or
photographs. Another
important job of forensic
odontology is in bite mark
analysis.
• Forensic Engineering
`
–These are concerned with
failure analysis, accident
reconstruction, and causes
and origins of fires or
explosions.
Forensic Entomology
Also Included: Maggot
Therapy and
Taxidermy
• Sung Tz'u (1235 AD) – Chinese
Historyinvestigator”
of Forensic Entomology:
“death
The Washing
Earliest Case
• Wrote The
Away of
Wrongs
• First forensic entomology case
recorded
• A murder by slashing occurred
in a village, and the local death
investigator was ordered to
solve the crime. The
investigator had all villagers
bring their sickles to one spot
Forensic Entomology
• Developmental
time Relies
is
Strongly on dependant
the Following at
temperature
Ecological Concepts
the microhabitat
level.
• Ecological succession – A
corpse will be invaded by a
series of different species
or insect groups over time.
Each species or group
changes the
microenvironment through its
Forensic Entomology is Involved With
Arthropod Involvement in Events
Surrounding Felonies
• Violent Crimes
–murder, suicide and rape
–physical abuse
–contraband trafficking
The Most Common Application
Relates to Death Investigations
• Determining PMI – postmortem
interval
• Movement of the corpse
• Manner and cause of death
• Association of suspects with the
death scene
• Detection of toxins or drugs
• Period
for Insects
a given
Estimatesof
of time
PMI Using
May
species to
a particular
Bereach
Based On:
stage of development
• Comparisons of assemblages
of insect fauna on corpse at
time of examination
• A combination of both above
Most Important Environmental
Factors in Corpse Decay*
• Temperature
• Access by insects
• Depth of Burial
• Necrophages – species feeding
Ecological
Roles of
Insectstrue
in
on corpse
tissue;
mostly
flies and Decompositon
beetles; age
determination (larval instar)
important for PMI
• Omnivores – insects that feed
both on the corpse and
associated fauna; ants, wasps
and some beetles; may alter
rate of decomposition
• Parasites and Predators – many
beetles, true flies and wasps
that attack immature flies
• Stage
One
Fresh
Stage
Five Stages of Human Decomposition Have
(Days 1-2)
From moment
Been–Recognized
of death to first sign of
bloating; flesh flies, blow
flies, ants eating fly eggs
and predatory wasps;
Flesh Flies – 2 Species
Two Blowfly Species
Blowfly Larvae
House Flies on Dead Host
• Stage two - Bloated stage
Five –Stages
…
(Days 2-6)
putrefaction
begins; gases produced by
anaerobic bacteria;
considerable bloating;
seepage of fluids; adult and
larval blowflies attracted in
large numbers to seepage;
soil fauna moves away due to
• Stage three - Decay Stage
Five Stages
…
(Days 5-11)
– Abdominal
wall
is broken and carcass
deflates; adult flies begin to
leave but great masses of
maggots remain and feed;
carcass will begin to dry and
beetles begin feeding on
drier tissue; flies start to
Pig Carcass Infested With Blowfly Maggots
Hister Beetles Prey on Blowfly
Larvae
Rove Beetles – 2 Species
• Stage Four - Postdecay
Five
Stages
… Stage 4
Stage
(Days
10-25)
–in dry habitats - remains
consist of dry skin,
cartilage and bones; site
for dermestid beetles,
histerids, fly pupae,
immature and adult rove
beetles
Dermestid Beetles – Adult and
Larvae
• Stage Five - Dry Stage
Five –Stages
… bone and
(Days 25+)
Mainly
hair is all that remains; odor
is primarily that of soil and
litter; some dermestids, fly
pupae, immature and adult
rove beetles, normal soil
fauna consisting of mites,
etc. start to return; this
Carrion Beetles – 2 Species
Female Carrion Beetle and
Kangaroo Rat
Rat will be completely buried and eggs
laid upon it.
• Physical
water, and
Barriers–tosoil,
Decomposition
caskets,
antermortem
Irregular
Decompositionand
postmotem injuries
• Chemical – embalming agent,
insecticides, lime, etc.
• Climatic – heat, cold, wind,
rainfall
• Animals – bird, mice,
rodents, canids, cats, etc.
Maggot Therapy – Technically called Maggot
Debridement Therapy or MDT
Fly larvae are used to scavenge on
dead tissue associated with a
wound.
Fly larvae excrement, termed
allantoin has a high ammonia
content which appears to serve as
an antibiotic.
Wounds on the Battlefield in World
War II
It has been noted by war
surgeons that wounds
incurred by troops in which
fly larvae were feeding had
much less gangrene and
healed more quickly than
wounds that were protected
from flies …
Phaenicia sericata – the green blow fly.
This species feeds only on necrotic
(decayed) tissue.
• Maggot therapy is much more
Interesting
…
commonly
usedand
in True
Great
Britain and Europe than in
the U.S.
• There have been about
25,000 treatments in Great
Britain since 1995.
• Ronald Sherman, M.D. is the
pioneer of maggot therapy in
Maggots Feeding at Edge of an
Ulcerating Wound on Foot
Maggots Cleaning Up a Wound
Associated with an Amputation
Vertebrate Biology/Taxidermy –
Skull and Skelton Preparation
A Skull Cleaned by
Dermestid Beetles
Trays of Vertebrate Skulls in Dept. Of
Vertebrate Biology, Univ. of Michigan
A Great Horned Owl Skeleton
Dermestid Colony Housing
Larval and Adult Dermestids
Working on Jawbone
Bear’s Skull Being Cleaned
Dermestid Beetles
Are Economic
Pests and
• Destroy
woolen
carpets,
Will Scavenge on Anything Organic of Both
upholestry
and
rugs
Plant and Animal Origin
• Consume insects on pins in
museum and university
collections
• Stored furs, leather and
skins
• Meat, cheese and stored
products
• Their use in vertebrate
Dermestids are Beneficial in Terms of
skull/skeleton collections
• Their forensic use as we
have seen