phone calls taper off Johnny Carson Comedian and television host 1 INTRODUCTION Human hair one of most frequently found pieces of evidence at scene of violent crime ID: 711231
Download Presentation The PPT/PDF document "HAIR “For three days after death, hair..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
HAIR
“For three days after death, hair and fingernails continue to grow but
phone calls taper off.”
—
Johnny Carson
Comedian and television hostSlide2
1
INTRODUCTION
Human
hair:
one
of
most
frequently found pieces of evidence at
scene
of
violent
crime.
can
provide
link
between
criminal
and
crime.Slide3
2
INTRODUCTION
From
hair one can determine:
If
source
is human or animal
Race (sometimes)
Origin of
location
on
source’s
body
Whether
hair
was forcibly removed
If
hair
has been treated with chemicals
If drugs have been ingestedSlide4
3
SKIN STRUCTURESlide5
4
HAIR SHAFT
Composed of:
Cuticle
outside covering
made
of overlapping
scalesSlide6
5
HAIR SHAFT
Composed of:
Cortex
inner
layer made of keratin and imbedded with
pigment
also
contains air sacs called cortical
fusiSlide7
6
HAIR SHAFT
Composed of:
Medulla
inside
layer running down
center
of
cortexSlide8
7
THE CUTICLE
outermost
layer of hair which is covered with scales.
scales
point toward
tip
of
hair
.
Scales
differ between species of
animals
named
based on their appearance
.
three basic patterns Slide9
8
CORONALSlide10
9
SPINOUSSlide11
10
IMBRICATESlide12
11
HUMAN SCALES
In order to visualize
scales
:
paint clear fingernail polish on
glass
slide
When polish
begins to dry, place
hair
on
polish
when almost dry, lift off
hair
and observe
scale
imprintsSlide13
12
Human Scales
What
pattern is seen in
this slide?Slide14
13
CORTEX
Gives hair
its shape.
has
two major
characteristicsSlide15
14
CORTEX
Melanin
pigment
granules that give hair its
colorSlide16
15
Cortex
Cortical
fusi
air spaces
usually
found near
root
but may be found throughout
hair
shaftSlide17
16
The Medulla
hair
core that is not always visible.
comes
in different types and patterns.Slide18
17
Medulla
Types
Intermittent
or interrupted
Fragmented
Continuous
Stacked
Absent
—
not presentSlide19
18
HUMAN MEDULLA
Human medulla may be continuous, fragmented or absent.Slide20
19
MEDULLARY INDEX
Determined
by measuring
diameter
of
medulla
and dividing it by
diameter
of
hair
.Slide21
20
MEDULLARY INDEX
human hair:
is generally less than 1/3.
animal hair:
usually
greater than 1/2.
mouseSlide22
21
HAIR SHAPE
Can
be straight, curly or
kinky
depending
on
cross-section
which
may be round, oval or crescent-shaped
Round
(Straight)
Oval
(Curly)
Crescent moon
(Kinky)Slide23
22
HAIR GROWTH
Grows
about 0.5 mm per day or 1 centimeter per
month
approximately
one half inch per monthSlide24
23
HAIR GROWTH
Anagen
hair
that is actively
growing
lasting
up to 5 yearsSlide25
24
HAIR GROWTH
Catagen
hair
is not
growing
resting
phaseSlide26
25
HAIR GROWTH
Telogen
hair
that is dying and ready to fall
out
lasting
two to six monthsSlide27
26
THE ROOT
Human roots
look
different based on
whether
they have been forcibly removed or if they are
telogen
hairs and have fallen out.
Animal
roots will vary, but in general have a spear shape.Slide28
27
THE ROOT
Fallen out
Forcibly removedSlide29
28
Hair Comparison
Color
Length
Diameter
Distribution, shape and color intensity of pigment granules
Dyed hair has color in cuticle and cortex
Bleaching removes pigment and gives a yellow tint
Scale types
Presence or absence of medulla
Medullary
type
Medullary
pattern
Medullary
indexSlide30
29
DNA FROM HAIR
root
contains nuclear DNA
.
If hair
has been forcibly removed, some
folicular
tissue may be attached containing DNA. Slide31
30
DNA FROM HAIR
hair
shaft contains abundant mitochondrial
DNA
inherited
only from
mother
.
can
be typed by comparing relatives if no DNA from
body
is available.
process
is more difficult and costly than using nuclear DNA.Slide32
31
COLLECTION OF HAIR
Questioned hairs must be accompanied by an adequate number of control samples.
from victim
from possible suspects
from others who may have deposited hair at
sceneSlide33
32
COLLECTION OF HAIR
Control
Sample
50 full-length hairs from all areas of scalp
24 full-length pubic hairsSlide34
33
HAIR TOXICOLOGY
Collections
must be taken from different locations on the body to get an accurate timeline.Slide35
34
HAIR TOXICOLOGY
Advantages:
Easy to collect and store
Is externally available
Can provide information on
individual’s
history of drug use or of poisoning
.Slide36
35
Hair Toxicology
Napoleon died in exile in 1821
.
By
analyzing his hair, some investigators suggest he was poisoned by
deliberate
administration of
arsenic
others
suggest that it was vapors from the dyes in
wallpaper
that did him in.