Serology PPT forensics
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Transcript Serology PPT forensics
Serology
Allie Wheeler, Amber Conrad, Aleisha Murrell,
Harsha Pinnamaraju, Orin Sparks, Jonathan Huynh,
Kyle Eberle
Table of Contents
Introduction…1
Objectives and Goals…2
Educational Requirements…3
Analytical Procedure…4
Presumptive Test…5
Blood Typing…8
Interpreting Blood Stain Patterns…12
Crime Scene Reconstruction…16
Glossary…23
Introduction
The following information presented is to help understand
serology, the study of blood, in forensic science. Blood is the
most common piece of evidence found at a crime scene and
is key to solving any crime. The following information is
presented:
Blood Typing
Blood Spatter
Crime Scene Reconstruction
Educational Requirements to be an Expert in this Field
And much more!
AW
Objective and Goals
Forensic Serology is dedicated to providing forensic analysis
of physical evidence to the criminal justice system.
Specialists analyze evidence, usually associated with blood, to
identify any suspects.
Tests and analysis are performed in controlled environment
using proper procedures in order to get accurate and relevant
analytical results.
HP,OS
Educational Requirements
Requirements for a general careers in this field:
formal education equivalent of a bachelor's degree in chemistry
or closely related field
bachelor's degree in biology
two years experience in a forensic laboratory
approval of the S.O.M.
School of Medicine
HP,OS
Analytical Procedures
Collection from Clothing or Other Items
Visual examine item
Take care to preserve evidence and other sections
such as blood, stains, and latent prints
At this point, you may use tape to remove stray
hairs and dust off the fiber
Label tape lifts
Identify fiber type and color
Place in envelope to store
HP,OS
Presumptive Tests
They are preliminary tests/field tests
Establishes possibility of a specific bodily fluid’s presence
Do not conclusively prove the presence
Pros:
Narrows possibilities
Can be used on larger areas
Can locate possible evidence not visible to naked eye
Cons:
Risk of false positives and may be overly sensitive
HP,OS
Presumptive Tests
Phenolphthalein Test
Aka: Kastle Meyer Test
A Phenolphthalein solution is used to show
the possible presence of blood based upon a
reaction of hemoglobin which produces a
pink color.
Precautions: This test is presumptive
because it has produced false positives
HP,OS
Presumptive Tests
LuminolTest
Luminol is used in solution or sprayed onto suspected surfaces.
This compound gives a strong blue fluorescence (glows)when
viewed with a UV light. It is used o find blood reminants
Precautions: False positives have been observed with the
presence of copper salts
HP,OS
Blood Typing
Blood Type
Antigens of Red Blood
Cells
Antibodies in Serum
A
A
Anti- B
B
B
Anti- A
AB
AB
Neither Anti- A nor Anti- B
O
Neither A or B
Both Anti- A and Anti- B
Anti- A Serum
Anti- B Serum
+
+
Whole Blood
Whole Blood
Antigen Present
Blood Type
+
-
A
A
-
+
B
B
+
+
A and B
AB
-
-
Neither A nor B
O
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Universal Types
People with type AB blood are called universal recipients
No antibodies present
Can receive blood from anybody
People with type O blood are called universal donors
No antigens present
Can donate blood to anybody
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Interpreting Blood Stain Patterns
Satellite Spatter: Small droplets of blood that are
distributed around the perimeter of a drop/drops
of blood and were produced as a result of the
blood impacting the target surface
Skeletonization: The outside of a blood droplet
will harden before the center
Drip Trail Pattern: A pattern of bloodstains
formed by the dripping of blood of a moving
surface or person in a recognizable pathway
separate from other patterns
AM,AC
Interpreting Blood Stain Patterns
Arterial Spatter: A characteristic blood stain
pattern containing spurts that result from
blood exiting under pressure from an arterial
injury
Expirated Blood Pattern: A pattern created by
blood that expelled out of the nose, mouth, or
respiratory system as a result of air pressure
and/or air flow
Void: Something that takes the place of the
blood at a crime scene
AM,AC
Interpreting Blood Stain Patterns
Transfer: A bloodstain pattern created
when a wet, bloody surface comes in
contact with a second surface.
Low Velocity Spatter: Blood that falls at a
normal gravity speed, typically from an
open wound
High Velocity Spatter: Blood that is flown
at a speed greater than that of gravity that
is associated with high-speed collisions,
such as gunshots or explosions
AM,AC
Interpreting Blood Stain Patterns
Impact Spatter: a random pattern of
spatter of varying sizes
Forward Spatter: Blood that travels
away from the source in the same
direction as the force that caused the
spatter
Back Spatter: Blood directed back
toward the source of the force that
caused the spatter
AM,AC
What is Crime Scene
Reconstruction?
The use of scientific methods,
physical evidence, deductive
reasoning and their interrelationships
to gain explicit knowledge of the
series of events that surround the
commission of a crime.
JH
Who Participates In Crime Scene
Reconstruction?
Reconstructing consists of the
following:
Medical Examiner
Experienced Law Enforcement
Personnel
Criminalists
JH
Steps of Crime Scene
Reconstruction
Recognition of evidence
Documentation of evidence
Collection of evidence
Evaluation of evidence
Hypothesis
Testing
Reconstruction
JH
Crime Scene Reconstruction
The criminalist must be prepared to answer the following
questions when examining dried blood
Is it blood?
From what species did the blood originate?
If the blood is of human origin, how closely can it be associated
to a particular individual
Detection of blood is best made by means of a preliminary
color test
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Things To Consider At The Crime
Scene
Origin(s) of bloodstain
Distance of bloodstain from target
Direction from which blood
impacted
Speed with which blood left source
Position of victim and assailant
Movement of victim and assailant
Number of blows/shots
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Which type of blood?
Once the stain has been
characterized as blood,
the precipitin test will
determine whether the
stain is of human or
animal origin
Once the bloodstain
has been determined to
be of human origin, the
blood is typed
Test For Human Blood
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Blood Group Characteristics
Based on 2 glycolipid antigens (A & B) found on the surfaces
of RBC
Antigen A only= type A blood
Antigen B only= type B blood
Both antigens= type AB blood
No antigens= type O blood
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Glossary
Agglutination: the clumping together of red blood cells by the action of an antibody
Angle of Impact: acute or internal angle formed by the direction of a blood drop and the plane of
the surface it strikes
Antibody: a protein in the blood serum that destroys or inactivates a specific antigen
Antigen: a substance, usually a protein, which stimulates the body to produce antibodies against it
Anti-Serum: blood serum that contains specific antibodies
Area of Convergence: The area containing the intersections generated by lines drawn through
the long axes of individual stains that indicates in two dimensions the location of the blood source.
Area of Origin: the location of the blood source in 3-D perspective
Arterial Spray: Bloodstain pattern(s) resulting from blood exiting the body under pressure from a
breached artery
Back Spatter: A bloodstain pattern resulting from blood drops that traveled in the opposite
direction of the external force applied; associated with an entrance wound created by a projectile.
Blood Drops: gravity acts on the blood until it impacts a horizontal surface
Blood Smears :these happen when a bleeding person is moved
Blood Splashes: blood that has been thrown through the air until it struck a surface at angle
AW
Glossary Cont.
Blood Spurts: this is result of arterial bleeding
Blood Trails: blood that is deposited when a wounded person walks or runs while dripping blood. It can
also happen from carrying or dragging a body
Drip Trail: A bloodstain pattern resulting from the movement of a source of drip stains between two
points.
Forward Splatter: A bloodstain pattern resulting from blood drops that traveled in the same direction as
the impact force.
High-Velocity Impact Spatter: bloodstains resulting from blood with a velocity in excess of 100 ft per
sec
Impact Spatter: A bloodstain pattern resulting from an object striking liquid blood.
Low-Velocity Impact Spatter: bloodstains resulting from blood with a velocity of 5 ft per sec or less
Luminal: a liquid that reacts to UV lighting and reveals that traces of blood
Medium Velocity Impact Spatter: bloodstains resulting from blood with a velocity of 5 ft to 25 ft per
sec
Plasma: the liquid part of the blood
Pools of Blood: these pools are next to the body and may indicate if the body has been moved
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Glossary Cont.
Satellite Spatter: A smaller bloodstain that originated during the formation of the parent stain as
a result of blood impacting a surface
Serology: the scientific study of blood
Skeletonization: A bloodstain consisting of a darkened peripheral rim where the center of the
stain is no longer intact.
Spattered Blood: a random distribution of bloodstains that vary in size that may be produced by a
variety of mechanisms
Transfer Patterns: A bloodstain resulting from contact between a blood-bearing surface and
another surface
Void: An absence of blood in an otherwise continuous bloodstain or bloodstain pattern.
AW
Works Cited
http://hemospat.com/terminology/index.php?cat=misc&s
ub=skeletonized
http://www.crimeandclues.com/index.php/forensic-
science-a-csi/crime-scene-investigation/crime-scenereconstruction/4-introduction-to-crime-scenereconstruction
http://www.wisegeek.com/what-are-the-differentcrime-scene-investigator-jobs.htm
http://www.cienciaforense.com/Pages/CrimeScene/C
SReconstruction.htm