Download powerpoint format

Microscopic Evidence
• HAIR EVIDENCE
• FIBER ANALYSIS
• PATHOLOGY INTRO
Microscopic Hair Analysis
The first step in microscopic hair evaluation is to
determine whether it is animal or human. Hair (and
nails) is made up of a protein called keratin, color and
trace minerals. A see-through outer covering called the
cuticle is composed of overlapping scales which can be
seen under the microscope. The pattern and shape of
the scales help to identify the type of animal or human
from which the hair originated. Human and animal
hairs differ on several physical characteristics including
Hair follicle= in dermis under skin
Hair shaft= the part we can see
Hair Analysis
• consistent pigmentation of the hair in humans
• a regularly-defined cellular core in animals
• a club-shaped root in humans with variable
shapes in animals
• animal coats contain several different types of
hairs while humans do not
Once the hair is identified as human, human
characteristics are determined which include:
race
•
•
•
•
body region from which the hair was found
length
color
whether the hair was removed forcibly from
the body
• damage due to crushing or burning
• chemical treatment such as dyes or bleach
Racial Variations
• Racial variations include the diameter of the hair
shaft, density and distribution of pigment
granules and shape of the hair in cross-section.
• Body hair is differentiated based on length, shaft
diameter, texture and condition of the tips.
• Comparing all of these characteristics allows a
forensic technician to determine if hair found at a
crime scene matches that of a suspect or victim.
Hair Shaft Layers
1. CUTICLE- outside layers that has scales
2. Cortex- middle layer- keratin bundles
3. Medulla- Central canal running through hair=
inner layer- has 3 basic patterns
CUTICLE
OVERLAPPING SCALES
– KERATINIZED
– FLATTENED
Most resistant to
chemical decomposition
is the cuticle
The SCALE PATTERN is most important in
identifying type of species.
MEDULLA
• CENTRAL CANAL
• PATTERNS
– CONTINUOUS
– INTERRUPTED
– FRAGMENTED
• SHAPE
MEDULLARY INDEX
• MEDULLA/HAIR SHAFT DIAMETERS
• HUMANS <1/3
HAIR COMPARISON
CAT
DOG
ORANGUTAN
RAT
Hair Samples
What is hair used for?
• Unless it is burnt, hair is extremely durable.
• It remains identifiable on bodies in an advanced state of
decomposition or attached to a murder weapon long after the
crime is committed.
• Hair is composed of protein substances, chiefly keratin, and
head hair grows at an average weekly rate of about 2.5mm, the
beard growing faster and body hair more slowly.
• Growth ceases at death, but as the skin shrinks the hair,
especially the beard, becomes more prominent, giving rise to
the murder myth that hair grows after death.
• The absorbent property of hair makes its examination
important in cases of arsenic poisoning.
• Hair picks up the poisons from the bloodstream, and it is
possible to work out the approximate strength and frequency
of the dosage by analysis.
What type of hair is CASHMERE
made from?
What type of hair is CASHMERE
made from?
GOAT
There is a breed of goat called
cashmere. Most raw cashmere
comes from China.
FIBER ANALYSIS
Cotton
Wool
Linen
Nylon
Silk
Rayon
COTTON
• Cotton is the most widely used plant fiber.
• Cotton fibers are the hairs found on the seeds of the cotton
plant.
• If possible, obtain a cotton boll on its stem.
• Examined under a microscope, the cotton fibers (use a few
strands of absorbent cotton) will look like a flattened,
irregular, twisted ribbon.
• Top three distributors:
– China, India, USA
WOOL
• Wool is the most commonly used animal fiber.
• The fiber is obtained from the soft, hairy covering of sheep and sometimes
goats.
• Under the microscope, the wool fiber looks like a long cylinder with scales
on it.
• The fiber is very curly and springy.
• Cloth made from wool includes cashmere, camel's hair, alpaca, covert
cloth, flannel, gabardine, mohair, serge, tweed and worsted.
LINEN
• Another common plant fiber is linen, which
comes from the flax plant.
• This fiber is long, lustrous, and smooth. Under the microscope it looks like
bamboo can, with jointed cells and split, tapered ends.
• Point out that linen is often used to make handkerchiefs, tablecloths,
napkins, summer clothing, pants and blouses.
SILK
• Silk, another common animal fiber, was once quite
popular, but has been replaced to a great extent by
such synthetic fibers as Nylon, Orlon, and Dacron.
• Silk is made by the mulberry silk worm when spinning
its cocoon.
• Under the microscope the silk fiber appears as a thin,
long, smooth and lustrous cylinder.
• Cloths made from silk include brocade, brocatelle,
chiffon, crepe, velvet, satin, taffeta, tulle, and falle.
• Silkworms (China) spin silk like spiders spin a web!
RAYON
• Rayon is one of the first successful artificial
fibers. It is made from cellulose.
• When manufactured, the rayon fibers
resemble silk.
• Under the microscope, the rayon fiber looks
like a smooth, lustrous cylinder.
• Rayon can be made into cloth that is hard to
distinguish from silk, cotton, linen, or wool.
• Celanese is one form of rayon.
ASBESTOS
• Asbestos is the name given to a group of minerals
that occur naturally as masses of strong, flexible
fibers that can be separated into thin threads and
woven to make asbestos cloth.
• These fibers are not affected by heat or chemicals
and do not conduct electricity.
• Asbestos cloth was used in fireproof theater
curtains and protective suits for use by fire
fighters.
• It was also used as a building material, brake pads
and a range of other products.
ASBESTOS
• It is now know that the fibers of asbestos are a
dangerous irritant.
• Even exposure to small amounts of asbestos dust
can lead to a range of illnesses such as asbestosis,
a serious lung inflammation caused by asbestos
exposure, and Mesothelioma a cancer of the
chest and abdomen.
• Although asbestos products are rarely made
these days, they can still be found, particularly in
old buildings.
Synthetic Fibers
• Today there is a wide variety of synthetic fibers;
all have trade names such as Nylon, Orlon,
Dacron, Vinyon, Aralac, Acrilan, Velon, Dynel,
Banlon and Lycra. Like rayon, these fibres
resemble silk, and under the microscope look like
smooth, lustrous cylinders.
• Synthetic fibers are easily identified because of
their uniform thickness (the thickness of natural
fibers varies).
• Synthetic fibers area made into fabrics that have
special properties..
Synthetic Fibers
• Glass and asbestos can also be spun into thread
and woven into fabrics.
• Glass fibers are made by stretching melted glass
into fine filaments, which are spun into thread for
weaving into cloth.
• Lightweight glass fibers are used to make long
lasting windows curtains, drapes, and lamp
shades.
• Heavier glass fabrics are used to make fireproof
theater and school curtains.
FORENSIC PATHOLOGY
A branch of pathology
concerned with determining
cause of death by observing
tissue, organs, bodily fluids
and whole bodies.
Sperm Cells
Sperm cells move by means of flagella
Terms to understand:
• CANCER- the uncontrolled growth of abnormal cells in
the body.
• Carcinoma = cancer
• Malignant tumor = cancer
• Benign tumor= not cancerous (moles/ fibroids)
– Limited growth (does not spread)
– Does not affect surrounding area
– Does not metastasize
– Some types of benign tumors can cause negative
health effects or can turn into malignant tumors
• Metastasis-the spread of a disease from one organ or
part to another non-adjacent organ or part.
Example of Metastasis
Primary cancer in pancreas which has caused
secondary liver tumors
CELLS:
Normal cells are uniform and arranged in tissues in an
orderly manner. When you poke and prod normal
tissue, it’s soft.
Paraganglioma shows polygonal chief cells
enclosed by fibrous elongated cells
OR Head/Neck Cancer Cells
Tumor cells have large, irregular nuclei, a small cytoplasm and
large variations in size and shape. The cells are arranged in a
disorganized fashion. Ex: Brain Tumor
A renal cell carcinoma stained slide
Lung Disease
Pathology of lung showing centrilobular emphysema
characteristic of smoking. Close-up of fixed, cut surface shows
multiple cavities (aveoli) lined by heavy black carbon deposits.
Slides to examine
Sketching the Evidence: