Identification
Personal identification methods:
I. Anthropometry:
This method depends on the accurate
measurement of certain parts of the adult body,
e.g. head, left arm, etc. This method is liable to
errors as a result of different measures taken by
different persons.
II. Portrait Parlé: includes the
following:
1. Description of the features.
2. Color of hair on the scalp, beard,
moustache and other parts of the body.
3. Color of the iris of the eye.
4. Description of any body peculiarities.
5. Description of any characteristic marks
on the body, e.g. scars or tattoo marks.
5. Photographs: side view and face view.
Photography in portrait parlé:
Side view and face view
N.B. Both anthropometry and
portrait parlé can not be relied
upon for sure in all cases of
personal identification.
III. Dactylography (fingerprints):
FINGERPRINTS CAN BE
CLASSIFIED INTO 4 MAIN GROUPS:
1. ARCHES.
2. LOOPS.
3. WHORLS.
4. COMPOSITE.
Classification of Fingerprints
The prints of each group can be
differentiated from each other by
their detailed structures, e.g.
bifurcations or unions of the ridges
forming the print.
Fingerprints are specific for each
person, i.e. there are no 2 persons
with identical fingerprints, even in
identical twins.
Detailed Structure of a Fingerprint
The pattern of the print is present
before birth (from the fourth month
of pregnancy, approximately), and
remains constant during the whole
life of the person.
The fingerprints will not disappear
except after operation or after the
application of caustics to them.
In such cases, there will be a scar
which is still a point of
identification.
After death and peeling of the
superficial layers of the skin as a
result of putrefaction, the deeper
skin layers will still carry the
characteristics of the print.
Personal identification by
dactylography is useful only
when there is a previous records
for these prints, to be used for
comparison.
Automated Comparing of Fingerprints
To take fingerprints of a person, his
fingerprints are moistened with
printer’s ink, then the impression of
each of his 10 fingers is taken and
preserved on a clean paper.
Poroscopy: is the study of the
sweat glands pores on the print,
after enlargement of a photograph
for that print. The number and
distribution of these pores is a
point of identification.
Poroscopy
IV. Bone
1. Determination of Sex
• Pelvis is the best bones (differences due to
adaptations to childbirth)
1. females have wider subpubic angle
2. females have a sciatic notch > 90°
3. females have a broad pelvic inlet
2.
3.
3.
1.
1.
2.
1. Determination of Sex
• Pelvis best (another view)
1. females have wider subpubic angle
2. females have a broad, shovel-like ilium
3. females have a flexible pubic symphysis
2.
3.
1.
2.
1.
1. Determination of Sex:
Cranium
• Crests and ridges more
pronounced in males (A,
B, C)
• Chin significantly more
square in males (E)
• Mastoid process wide
and robust in males
• Forehead slopes more in
males (F)
Determination of Age
•
•
The long bones are
those that grow
primarily by
elongation at an
epiphysis at one end
of the growing bone.
The long bones
include the femurs,
tibias, and fibulas of
the legs, the humeri,
radii, and ulnas of the
arms, and the
phalanges of the
fingers and toes.
As a child grows the
epiphyses become
calcified (turn to hard
bone)
Epiphyseal Fusion
• The figures below are of the Epiphyses of the femur or thigh bone (the
ball end of the joint, joined by a layer of cartilage).
• The lines in the illustrated Image 1 show the lines or layers of cartilage
between the bone and the epiphyses. The lines are very clear on the
bone when a person, either male or female is not out of puberty.
• In Image 2, you see no visible lines. This person is out of puberty. The
epiphyses have fully joined when a person reaches adulthood, closing off
the ability to grow taller or in the case of the arms, to grow longer.
Figure 1.
Figure 2.
Cartilage is darker on xray than
solid bone. Epiphyses aren’t fused
yet.
No cartilage visible. Epiphyses are
fused.
•Union of epiphysis:
•Trochlea fuses with capitulum (humerus) : 14 years
•Illeum, ischium and pubis unite with acetabulum:
15 years
•Troholea and captulum with the shaft of humerus:
15 years
•Lateral epicondyle of humerus: 16 years
•Upper end of ulna: 16 years
•Lesser trochanter of femur: 16 years
•Medial epicondyle of humerus : 17 years
•Upper end of radius: 17 years
•Greater trochanter of femur: 17 years
•Epiphysis of metacarpals and phalanges: 18 years
•Head of the femur: 18 years
•Lower end of tibia: 18 years
•Head of the humerus: 20 years
•Distal end of radius: 20 years
•Distal end of ulna: 20 years
•Upper end of tibia: 21 years
•Lower end of femur: 21 years
•Epiphysis of ischial tuberosity: 21 years
•Epiphysis of iliac crest: 20- 25 years
•Basi-occiput with basi-sphenoid: 20- 25
years
Fusion of suturs of the skull:
•Sagital suture: 25- 30 years
•Coronal suture: 40 years
•Lambdoid suture: 50 years
V. Teeth
Age of 6 – 24 months is identified by
milk dentition as follow:
Central incisors : 6 months
Lateral incisors: 9 months
First milk molar: 12 months
Canine: 18 months
Second milk molar: 24 months
Age of 6 – 12 years is identified by
permanent dentition as follow:
First permanent molar: 6 years
Central incisors: 7 years
Lateral incisors: 8 years
First permanent premolar: 9 years
Second permanent premolar: 10 years
Canine: 11 years
Second permanent molar: 12 years
Third permanent molar : 17 – 25
VI. BLOOD
Question 1: Is the stain blood or
not?
Preliminary tests:
1. They depend on the presence of the oxidase
enzyme in blood.
2. The oxidase enzyme helps oxidation of the
oxidizable substances in these tests such as
(Guiacum, Benzidine and Kasle-Meyer or
Phenolphthalein test).
3. The oxidation occurs in the presence of oxygen
source such as H2O2.
4. The oxidation is identified by the change of
color of reagents used.
5. They can be carried out on a filter paper.
Guiacum test: ½ cc of stain
extract + ½ cc Guiacum reagent +
½ cc H2O2 → green color. It is
sensitive up to 1/5.000 of blood
dilutions.
Benzidine test: ½ cc of stain
extract + ½ cc benzidine reagent +
½ cc H2O2 → blue color. It is
sensitive up to 1/300.000 of blood
dilutions.
Kastle-Meyer test: ½ cc of stain
extract + ½ cc Kastle-Meyer
reagent + ½ cc H2O2 → pink color.
It is sensitive up to 1/5.000.000 of
blood dilutions.
Conclusions: If preliminary tests are
negative so the stain is not blood.
However, if the preliminary tests are
positive so the stain may be blood or
some stain else. So we proceed to
the confirmatory tests.
Confirmatory tests:
Michrochemical,
Microscopic,
Spectroscopic tests.
Microchemical tests:
Teichman test and Takayama test.
Teichman test (Haemin crystal test):
It is done on a slide. Small fragments
of the stain + a few drops of
Teichman reagent, then cover and
heat gently, then leave slide to cool
down. After that examine the slide
under low power microscope if +ve
test gives: Small brown rhombic
crystals of haemin.
Takayama test (Haemochromogen
crystal test):
It is done on a slide as well. Small
fragments of the stain + a few drops of
Takayama reagent, then cover and heat
gently, then leave slide to cool down.
After that examine the slide under low
power microscope if +ve test gives: Pink
needle-shaped crystals of
haemochromogen.
Microscopic test: under microscope, blood
cells can be seen, especially RBCs.
Advantages of the spectroscopic test:
1. Simple and easy.
2. Applied on a very little amount of blood stain.
3. Does not interfere with the subsequent
chemical tests.
4. It helps in the detection of certain toxins such
as cyanide, carbon monoxide, Hydrogen sulfide.
5. In these tests we obtain the characteristic
absorption bands by examination through
spectroscope, so, we can see and detect
absorption bands.
Spectroscope
1. Oxy Hb: 2 absorption bands between
D and E lines of the spectrum.
2. Reduced Hb: prepared by addition of
oxy Hb to reducing reagents such as
yellow ammonium sulfide or sodium
hydrosulphide. Reduced Hb gives one
broad band between D and E lines.
3. Carboxy Hb: prepared by passing
CO gas on oxy Hb. Carboxy Hb gives 2
bands of oxy Hb (Bet D and E lines)
but they are shifted to the right.
4. Met Hb: Gives 2 bands between D
and E lines and a third band between C
and D lines.
5. Haemochromogen: Gives one band
between D and E lines, in addition to
another band to the right of E line.
N.B. Haemochromogen can be
prepared by a few drops of
takayama reagent + Oxy Hb.
Question 2: Is it blood of human or
animal? Microscopic and precipitin
tests:
Microscopic test: applied to fresh blood
only:
1. Human RBCs :
- Rounded and biconcave
- Non nucleated
- Form a rouleaux
- Average diameter is 7 microns.
2. Camel’s RBCs:ovel and non-nucleated
3. Non-mammalian RBCs e.g. frog: Oval,
large and nucleated.
Precipitin test: It depends on an
antigen-antibody reaction, when
positive results in precipitation.
Question 3: Does blood belong to
a certain person?
ABO Blood grouping:
HUMAN BLOOD CAN BE DIVIDED
INTO 4 MAIN GROUPS: A, B, AB,
AND O.
ABO Blood Grouping
Blood Group
A
Agglutinogen on Agglutinin in the
the surface of the person’s serum
RBCs
A
Beta
B
B
AB
AB
Alpha
--------------------O
Alpha, Beta
---------------------
Grouping of fresh blood:
1. A citrated blood sample is
diluted with saline.
2. One drop of this diluted blood
is put near the end of a clean
glass slide.
3. Another drop is put neat the
other end of the slide.
Steps of blood grouping:
1. Add one drop of anti-A serum to the
first drop on the slide.
2. Add one drop of anti-B serum to the
second drop on the slide.
3. Mix and allow to stand for a few
minutes.
4. Examine for agglutination, both by
naked eye, and by the low power of
microscope.
Results of Blood Grouping Test
Diluted blood +
anti-A serum
Agglutination
Diluted blood + Individual’s
anti-B serum
blood group
No agglutination Blood group A
No agglutination Agglutination
Blood group B
Agglutination
Blood group AB
Agglutination
No agglutination No agglutination Blood group O
Blood Grouping Test Result
VII :Identification of semen
Physical characters: fresh semen is
stick with a characteristic odor,
while old semen is starchy,
yellowish and fluoresces when
exposed to ultra-violet light.
Microchemical tests:
1- Florence test
• Florence test (for detection of choline): on
clean glass slide, one drop of stain soaking +
one drop of Florence iodine reagent: in
positive cases, evanescent large brown
rhombic crystals, consisting from choline diiodide.
Large brown rhombic crystals of
positive Florence test for semin.
2- Barberio’s test
• Barberio’s test (for detection of spermine): on
clean glass slide, one drop of stain soaking +
one drop of barberio’s reagent: in positive
cases, yellow needle-shaped crystals.
Yellow needle-shaped crystals are seen
in positive Barberio’s test for semin.
3- Acid phosphatase test.
4- Prostatic –specific antigen test
(p30).
Microscopical examination of seminal
stains for presence of spermatozoa.
Microscopic detection of one
complete spermatozoon is necessary
to conclude the presence of semen.
Microscopical examination of seminal
stains for the presence of spermatozoa.
VIII. Deoxyribo-Nucleic Acid
(DNA)
DNA IS THE GENETIC MATERIAL
WHICH CARRIES THE GENETIC
INFORMATION RELATED TO THE
PERSON.
IT EXISTS IN ALL BODY CELLS
EXCEPT RBCS AS THEY ARE NONNUCLEATED.
DNA Collection & Comparison:
• DNA is collected at crime scenes in a variety
of ways using tools such as:
• Smear slides, scalpels, tweezers, scissors,
sterile cloth squares, UV light, luminol and/or
blood collection kits (for sample collection of
suspects or living victims)
Saliva, blood, hair strands, skin, finger
or toe nails, and/or a tooth with root
material.
**Note: There must be cells with
nuclei present before nDNA
can be obtained.**
How is blood collected?
1. Blood on Clothing?
Investigators submit whole pieces of
clothing or they may use a sterile cloth
square and a small amount of distilled
water.
2. Dried blood on furniture?
Investigators send the whole object
to the lab.
3. Dried blood on a wall, tub or some
other object too big or difficult to
move to the lab?
4. Investigators scrape the blood
sample into a sterile container for
further analysis.
Types of DNA in the mammalian
cell: nuclear and mitochondrial.
Two DNA Types in a Human Cell
Nucleus
Mitochondria
Evidentiary DNA Extraction
Evidentiary PCR Prep
• Physically separated Thermal Cycling Room
for Evidentiary Samples
Applications of Nuclear DNA in
Human Identification
• Sexual assault cases and other violent crimes
(forensics)
• Exoneration of convicted persons (innocence
projects)
• Identify serial crimes (DNA databasing)
• Identify biological parents (paternity)
• Identify other biological relationships (sibship)
• Identify human remains (missing persons)
• Infidelity testing (semen screening)
Applications of Mitochondrial DNA in
Human Identification
•
•
•
•
•
Maternal relationships
Forensics
Missing persons investigations
Identification of victims of mass disasters
Military actions and repatriation
Nuclear Vs. Mitochondrial DNA
Characteristics
Nuclear DNA
(nDNA)
Mitochondrial DNA
(mtDNA)
Location within In Nucleus
the Cell
In Cytoplasm
DNA Structure
Linear Double helix
“Twisted Ladder”
Exactly same as nDNA
but circular like “twisted
rubber band”
DNA Length
More than 3 billion
bases
Only 16,569 bases
DNA Copy
Number
Two copies of each
segment called a locus
(plural-loci)
A few hundreds
thousands copies
to
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