dec 28:10 pm · 2011-04-01 · 24 dec 210:48 pm evaluation use comparison microscope presumptive...
TRANSCRIPT
1Dec 28:10 PM
Hair
*credit to Anthony and Patti Bertino for image
2Dec 28:12 PM
Essential Question:
How can hair be used to solve a crime?
3Mar 136:58 AM
History of hair evidencecriminal evidence in 1800's1883 The Principles and Practice of Medical Jurisprudence
by Alfred Swain Taylor and Thomas Stevenson chapter on hair evidence, drawings under magnificationreferences cases in Englanddiscusses structure of hair
1910 Le Poil de l'Homme et des Animaux by Victor Balthazard and Marcelle Lambertmicroscopic drawings
1934 use of comparison microscope by Dr. Sydney Smith
late 20th century DNA fingerprinting, neutron activation analysis
4Mar 137:03 AM
Function of hair (tricology study of hair)
1. regulate body temperature (arector pili)
2. decreases friction
3. protects against sunlight
4. sense organ
5 million hair follicles when born 2% on headlose hair as we age
* hair does not continue to grow after death
5Dec 28:14 PM
Hair evidence:
• class evidence • indicates contact • used as supporting evidence• resistant to chemical decomposition• retains structural features for a long time
6Dec 28:29 PM
Morphology of hair:
hair follicle organ located in the scalp hair grows out of here
bulb
root
shaft
http://www.follicle.com/hairstructurelifecycle.html
7Dec 28:38 PM
Shaft structure:(*think pencil)
cuticle: outer most layerformed by overlapping scales
scales point to tip of hairhelps identify animal speciescan make a cast of pattern using nail polish or
softened vinyl
http://www.thegentletouch.com/hairbiol/hmorph6.htm
8Dec 28:54 PM
cortex:within cuticlemain body of hair shaft largest partspindle shaped cells, parallel to length of hairhas pigment granules (melanin) that give hair colorviewed under microscope after put in liquid medium with
similar refractive index
pig hair 100X *credit to Anthony and Patti Bertino for image
9Dec 29:16 PM
medulla:= middlelooks like central canal in some animals stands out, 1/2 of hair diametermedullary index= diameter of medulla relative to diameter
of hair shafthumans =< 1/3, 0.33 animals = >1/2, 0.50
medullas vary person to personclassification:
continuousinterruptedfragmentedabsent
cat medulla
rat 400X
10Oct 18:53 AM
To distinguish between animal and human hair use a Medullary Index
diameter of hair’s medullaMedullary Index =
diameter of the hair
M.I. = <.33 hair is humanM.I. =>.5 or more, hair is animal
*credit to Anthony and Patti Bertino for this slide
11Oct 18:33 AM
Types of Medullas
*credit to Anthony and Patti Bertino for image
12Dec 29:44 PM
different animal medullas:
Bat Hair400X
Cow hair100X
horse hair 400X
fragmented
continuous
13Mar 137:15 AM
Hair varies
shape round, oval, triangular, flattened
length
diameter
texture coarse, fine
color pigment granules, dyes
sampling: 50 hairs from head, 25 pubic hairs
*credit to Anthony and Patti Bertino for image
14Mar 137:17 AM
Hair types on body:
Head
eyebrows/ eyelashes
underarm
beard/ mustache
auxilary (body hair)
pubic
15Dec 29:45 PM
head hairs: usually no medulla or fragmented Mongoloid race usually have continuous
medullasanimals usually have continuous or interrupted
have database of 35 most common animal hairs for comparison
16Oct 18:38 AM
*credit to Anthony and Patti Bertino for images
Caucasian
Oriental (Mongoloid)
Negroid
17Oct 18:44 AM
Hair from different races
Negroid Mongoloid Caucasoid
*credit to Anthony and Patti Bertino for images
18Oct 18:47 AM
Additional Information
• Individuals of oriental origin usually have a continuous medulla
• Dyed hair shows color distributed in cortex and medulla
• Bleached hair has a yellowish tint• As hair grows, natural color returns
*credit to Anthony and Patti Bertino for this slide
19Dec 210:12 PM
Root:produces hair three stages life cycle
a. anageninitial growth phase, hair follicle produces hair, up to 6 yrs. (80%90% in this phase)
if pulled out of scalp has follicular tag (DNA)b. catagentransition phase, 23 weeks (2% in this phase)c. telogen final growth phase, hair falls out 26 months
20Dec 210:29 PM
Identification:establish animal or humandetermine if hair at crime scene matches a particular
individual
animal vs. human easily done
cat hair 400X human hair 100X
21Dec 39:04 AM
human comparisons difficult• varies within individuals• match color, length and diameter• other features: presence or absence of medulla,
distribution, shape, and color intensity of pigment granules
• dyed and bleacheddye found in cuticle and cortex bleach removes pigment and give yellowish
tint
• estimate time with dyed hair 1cm/month
22Mar 138:42 AM
Human vs. animal differences
pigmentationhumans denser toward cuticleanimals denser toward medulla
solid masses called ovoid bodies, esp. dogs, cattle
colorhumans usually one color along lengthanimals can change color abruptly, banded
appearance
23Oct 18:42 AM
Medullalarger in animals than humans
cuticlehuman imbricateanimals coronal crown like (rodents, bats)
spinous petal like (cats, seals, mink)
24Dec 210:48 PM
evaluation use comparison microscope
presumptive evidencephase contract microscope
refractive indexfluorescent microscope
dyes fluoresce confirmed by DNA
can tell which part of the body where hair is fromhead little diameter variation, uniform pigmentation pubic short curly beard coarse, triangular cross section, blunt tips
age hard to tell gender can tell from DNA, amelogenin gene
http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm
25Mar 138:49 AM
Testing for substances (toxins, drugs) in hair
chemical analysishair dissolved in solvent breaks down keratin to release substancesthen do chemical analysis (GCMS)
Neutron activation analysis (NAA)hair placed on nuclear reactor and bombarded with high energy neutronsdifferent elements give off gamma radiation with different signalssignals are recorded to determine concentrationcan id antimony, argon, bromine, copper, gold, manganese,
silver, sodium, zinc1 in a million chance a hair has same concentrations of all nine
elements
26Mar 138:56 AM
DNA analysis
follicular tag when follicle is pulled out with hair, can run DNA, blood test
DNA can individualize hair nuclear DNA mitochondrial DNA can't individualize, siblings would have the same mtDNA
usually do microscopic examination first, then if believed to match, a DNA test
27Dec 39:00 AM
razor cut hair split hair hair with cut tip
Can tell if hair was cut recently by looking at the ends
http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm
28Dec 211:11 PM
can tell if pulled out if has follicular tissue = pulled out forcibly or by brush sheath shells usually present if quickly pulled out
naturally shed forcibly removedshows stretching
forcibly removedwith tissue attached
29Dec 211:16 PM
Collection and preservation:hair from crime scene if dry, druggist fold
if wet, dry first then in paper envelopestandard comparison samples
50 full length head hairs pulled from scalp or cut at skin line
24 full length pubic hairsif rape case, must first comb area to remove foreign
hair during autopsy
hair samples collected from victim