Have you seen any of these
television shows?
• CSI
• Criminal Minds
• NCIS
• Law and Order
• Bones
Forensic Science
T. Trimpe 2006 http://sciencespot.net
Crime Scene Vocabulary
CRIME SCENE: Any physical location in which a crime has occurred or is
suspected of having occurred.
PRIMARY CRIME SCENE: The original location of a crime or
accident.
SECONDARY CRIME SCENE: An alternate location where
additional evidence may be found.
SUSPECT: Person thought to be capable of committing a crime.
ACCOMPLICE: Person associated with someone suspected of committing a crime.
ALIBI: Statement of where a suspect was at the time of a crime.
Source: http://www3.sc.maricopa.edu/ajs/crime_scene_technician.htm
Types of Evidence
Testimonial evidence includes oral or written statements given to police as well as
court testimony by people who witnessed an event.
Physical evidence refers to any material items that would be present at the crime
scene, on the victims, or found in a suspect’s possession.
Trace evidence refers to physical evidence that is found in small but measurable
amounts, such as strands of hair, fibers, or skin cells.
What will evidence collected at a scene do for the investigation?
• May prove that a crime has been committed
• Establish key elements of a crime
• Link a suspect with a crime scene or a victim
• Establish the identity of a victim or suspect
• Corroborate verbal witness testimony
• Exonerate the innocent.
• Give detectives leads to work with in the case
Source: http://www3.sc.maricopa.edu/ajs/crime_scene_technician.htm
Crime Scene Personnel
POLICE OFFICERS are typically the first to arrive at a crime scene. They are
responsible for securing the scene so no evidence is destroyed and detaining
persons of interest in the crime.
The CSI UNIT documents the crime scene in detail and collects any physical
evidence.
The DISTRICT ATTORNEY is often present to help determine if any search
warrants are required to proceed and obtains those warrants from a judge.
The MEDICAL EXAMINER (if a homicide) may or may not be present to
determine a preliminary cause of death.
SPECIALISTS (forensic entomologists, anthropologists, or psychologists) may be
called in if the evidence requires expert analysis.
DETECTIVES interview witnesses and consult with the CSI unit. They
investigate the crime by following leads provided by witnesses and physical
evidence.
Source: http://science.howstuffworks.com/csi.htm
Crime Scene Protocol
Step 1: Interview
The first step in investigating a crime scene is to interview the first officer at the scene or the
victim to determine what allegedly happened, what crime took place, and how was the
crime committed. This information may not be factual information but it will give the
investigators a place to start.
Step 2: Examine
The second step in the investigation of a crime scene, which will help identify possible
evidence, identify the point of entry and point of exit, and outline the general layout of the
crime scene.
Step 3: Document
The third step in the protocol involves creating a pictorial record of the scene as well as a
rough sketch to demonstrate the layout of the crime scene and to identify the exact
position of the deceased victim or other evidence within the crime scene.
Step 4: Process
This is the last step in the protocol. The crime scene technician will process the crime scene
for evidence, both physical and testimonial evidence. It is the crime scene technicians
responsibility to identify, evaluate and collect physical evidence from the crime scene for
further analysis by a crime laboratory.
Adapted from http://www.feinc.net/cs-proc.htm
Investigating the Evidence
Forensic Science disciplines at the
Illinois State Police Crime Labs
Drug Chemistry – Determines the presence of controlled substances and the identification
of marijuana
Trace Chemistry - Identification and comparison of materials from fires, explosions, paints,
and glass.
Microscopy – Microscopic identification and comparison of evidence, such as hairs, fibers,
woods, soils, building materials, insulation and other materials.
Biology/DNA – Analysis of body fluids and dried stains such as blood, semen, and saliva.
Toxicology – Tests body fluids and tissues to determine the presence of drugs and poisons.
Latent Prints - Identification and comparison of fingerprints or other hidden impressions
from sources like feet, shoes, ears, lips or the tread on vehicle tires.
Ballistics (Firearms) – Study of bullets and ammunition through the comparison of fired
bullets, cartridges, guns, and gunpowder patterns on people and objects.
Toolmarks – Examines marks left by tools on objects at a crime scene or on a victim, such
as a hammer used to break a door or a screwdriver used to pick a lock.
Questioned Documents - Examination of documents to compare handwriting, ink, paper,
writing instruments, printers, and other characteristics that would help to identify its origin.
Source: http://www.isp.state.il.us/forensics/
What evidence would you collect?
Mock Crime Scene: http://www.masss.gov
Forensic Science
T. Trimpe 2006 http://sciencespot.net/
What makes up our blood?
• RED BLOOD CELLS (Erythrocytes) – The most abundant
cells in our blood; they are produced in the bone marrow and
contain a protein called hemoglobin that carries oxygen to our
cells.
• WHITE BLOOD CELLS (Leukocytes) – They are part of
the immune system and destroy infectious agents called
pathogens.
• PLASMA – This is the yellowish liquid portion of blood that
contains electrolytes, nutrients and vitamins, hormones,
clotting factors, and proteins such as antibodies to fight
infection.
• PLATELETS (Thrombocytes) – The clotting factors that are
carried in the plasma; they clot together in a process called
coagulation to seal a wound and prevent a loss of blood.
Blood Facts
The average adult has about FIVE liters of blood inside of
their body, which makes up 7-8% of their body weight.
Blood is living tissue that carries oxygen and nutrients to
all parts of the body, and carries carbon dioxide and other
waste products back to the lungs, kidneys and liver for
disposal. It also fights against infection and helps heal
wounds, so we can stay healthy.
There are about one billion red blood cells in two to three
drops of blood. For every 600 red blood cells, there are
about 40 platelets and one white cell.
http://www.bloodbankofalaska.org/about_blood/index.html
Genetics of Blood Types
• Your blood type is established before you are BORN,
by specific GENES inherited from your parents.
• You inherit one gene from your MOTHER and one
from your FATHER.
• These genes determine your blood type by causing
proteins called AGGLUTINOGENS to exist on the
surface of all of your red blood cells.
What are blood types?
There are 3 alleles or genes for blood
type: A, B, & O. Since we have 2 genes,
there are 6 possible combinations.
Blood Types
AA or AO = Type A
BB or BO = Type B
OO = Type O
AB = Type AB
http://learn.genetics.utah.edu/units/basics/blood/types.cfm
How common is your blood type?
46.1%
38.8%
11.1%
3.9%
Blood Transfusions
A blood transfusion is a procedure in which blood is given to a patient through an
intravenous (IV) line in one of the blood vessels. Blood transfusions are done to replace
blood lost during surgery or a serious injury. A transfusion also may be done if a person’s
body can't make blood properly because of an illness.
Who can give you blood?
Universal Donor
People with TYPE O blood are called
Universal Donors, because they can give
blood to any blood type.
People with TYPE AB blood are called
Universal Recipients, because they can
receive any blood type.
Rh +  Can receive + or Rh -  Can only receive Universal Recipient
Rh Factors
• Scientists sometimes study Rhesus monkeys
to learn more about the human anatomy
because there are certain similarities between
the two species. While studying Rhesus
monkeys, a certain blood protein was
discovered. This protein is also present in the
blood of some people. Other people, however,
do not have the protein.
• The presence of the protein, or lack of it, is
referred to as the Rh (for Rhesus) factor.
• If your blood does contain the protein, your
blood is said to be Rh positive (Rh+). If your
blood does not contain the protein, your blood
is said to be Rh negative (Rh-).
http://www.fi.edu/biosci/blood/rh.html
A+ AB+ BAB+ ABO+ O-
Blood Evidence
• Blood samples – Can be analyzed to determine blood
type and DNA, which can be matched to possible
suspects.
• Blood droplets – Can be analyzed to give clues to the
location of a crime, movement of a victim, and type of
weapon.
• Blood spatter – Can be analyzed to determine
patterns that give investigators clues to how a crime
might have happened.
Microscopic
Views
Fish Blood
Bird Blood
Horse Blood
Frog Blood
Cat Blood
Dog Blood
Human Blood
Snake Blood
Forensic Science Lab Activity
Warning: Some material in this presentation and
related videos may be too graphic for some people.
T. Trimpe 2006 http://sciencespot.net/
What does the abbreviation BPA represent? Bloodstain Pattern Analysis
What can an investigator learn from the analysis of a blood spatter?
 Type and velocity of weapon
 Number of blows
 Handedness of assailant (right or left-handed)
 Position and movements of the victim and assailant during and after the attack
 Which wounds were inflicted first
 Type of injuries
 How long ago the crime was committed
 Whether death was immediate or delayed
Source: http://science.howstuffworks.com/bloodstain-pattern-analysis1.htm
http://www.crimescenetwo.com/img/popup/book2p2.jpg
How is blood evidence detected at a crime scene?
Light Source
Investigators will first examine the crime scene to look for areas
that may contain blood. They may use a high-intensity light or
UV lights to help them find traces of blood as well as other bodily
fluids that are not visible under normal lighting conditions.
Blood Reagent Tests
These tests, referred to as presumptive tests, are used to detect
blood at crime scenes based upon the properties of hemoglobin in
the blood. Further tests at the crime lab can determine if it is
human blood or not.
Kastle-Meyer Test
Video
Examples:
• Phenolphthalein is a chemical that is still utilized today and is
usually referred to as the Kastle-Meyer test and produces a pink
color when it reacts with hemoglobin.
•HemaStix is a strip that has been coated with
tetramethylbenzidine (TMB) and will produce a green or bluegreen color with the presence of hemoglobin.
HemaStix
Luminol
This chemical is used by crime scene investigators to locate traces of
blood, even if it has been cleaned or removed.
Investigators spray a luminol solution is throughout the area under
investigation and look for reactions with the iron present in blood, which
causes a blue luminescence.
One problem is that other substances also react, such as some metals,
paints, cleaning products, and plant materials. Another problem is that the
chemical reaction can destroy other evidence in the crime scene.
Fluorescein
This chemical is also capable of detecting latent or old blood, similar to
luminol. It is ideal for fine stains or smears found throughout a crime
scene. After the solution has been sprayed onto the substance or area
suspected to contain blood, a UV light and goggles are used to detect any
illuminated areas, which appear greenish-white if blood is present. It may
also react to many of the same things as luminol (copper and bleach).
Luminol
Reaction
Fluorescein
Reaction in
UV Light
LCV or Leuco Crystal Violet, is one type of chemical process that is used for blood
enhancement. Using this test helps to make the blood evidence more visible so it can be
photographed and analyzed.
Bloodstain Pattern Analysis Terms
• Spatter – Bloodstains created from the application of force to the area
where the blood originated.
• Origin/Source – The place from where the blood spatter came from or
originated.
• Angle of Impact – The angle at which a blood droplet strikes a surface.
• Parent Drop – The droplet from which a
satellite spatter originates.
• Satellite Spatters – Small drops of blood
that break of from the parent spatter when
the blood droplet hits a surface.
• Spines – The pointed edges of a stain that
radiate out from the spatter; can help
determine the direction from which the
blood traveled.
Satellite Spatters
Spines
Parent Drop
Types of Bloodstain Patterns
Blood Spatter
Movie
• Passive Bloodstains
– Patterns created from the force of gravity
– Drop, series of drops, flow patterns, blood pools, etc.
• Projected Bloodstains
– Patterns that occur when a force is applied to the
source of the blood
– Includes low, medium, or high impact spatters, castoff, arterial spurting, expiratory blood blown out of
the nose, mouth, or wound.
• Transfer or Contact Bloodstains
– These patterns are created when a wet, bloody object
comes in contact with a target surface; may be used to
identify an object or body part.
– A wipe pattern is created from an object moving
through a bloodstain, while a swipe pattern is created
from an object leaving a bloodstain.
Images from http://www.bloodspatter.com/BPATutorial.htm
Blood Spatter Labs
• You will be creating sample drop patterns using single drops and
multiple drops. We will also investigate the effect of motion and the
angle of impact on blood spatter.
• This can be messy! Be very careful to keep the blood on the paper
and not on yourself, the table, or floor.
• Hold you hand as steady as possible when making the drops.
Brace your wrist against the meter stick to help you.
• Get your materials from your teacher – paper, black marker, meter
stick, goggles, and a bottle of blood.
If you make a mess, clean it up immediately!
Lab 1: Single Droplets
• Label two large pieces of construction paper as shown below.
Single Drops
Group Members
Single Drops
Group Members
Keep your drops
in the correct area
of the paper.
25
50
75
100
• To do the lab, put on your goggles and hold the dropper bottle upside down so
that the end of it is 25 cm from the paper. GENTLY squeeze the bottle so that ONE
drop of blood is released and lands in the correct location on your paper. It should
NOT hit the meterstick.
• Repeat TWO more times at this height for a total of three drops.
• Continue making drops of blood on your paper, but put the drop in a different
area of the paper and change the height each time.
• When you are done, analyze your results and answer the questions on your
worksheet.
Make a mistake? Use a paper towel to wipe it off your paper!
Lab 1 Questions
Use your results to answer these questions.
What did you notice about the diameter of the parent droplets as you increased the
height of the drop?
How do the spines compare from the different heights?
Lab 2: Multiple Droplets
• Label a long piece of butcher paper (2 -3 meters in length) as shown below.
Multiple Drops
Group Members
Keep your drops
in the correct area
of the paper.
25
50
75
100
• To do the lab, put on your goggles and hold the dropper bottle upside down so that
the end of it is 25 cm from the paper. GENTLY squeeze the bottle so that ONE drop
of blood is released and lands in the correct location on your paper. The drop should
NOT hit the meterstick.
• Without moving your hand, release ONE more drop onto the first drop at that
height. If you make a mistake, wipe it off with a paper towel and try it again.
• Continue making drops of blood on your paper so you have three sets for each
height.
• When you are done, analyze your results and answer the questions on your
worksheet. Clean up your area and put away your materials before you leave class.
Lab 2 Questions
Use your results to answer these questions.
What happened when one drop landed on top of another one?
What did you notice about the diameter of the parent droplets as you increased the
height of the drop?
What do you notice about the diameter of the satellite spatter as you increased the
height of the drop?
Lab 3: Motion Droplets
• During this lab, you will see how motion affects the size and shape of the
droplets and spines. You will need a long piece of butcher paper (4-5 meters in
length) and tape to secure it to the floor. You will also need safety goggles.
• To do the lab, you will need to hold the dropper bottle upside down so that your
hand is out and away from your body (waist level), but is still over the paper.
• Start off walking at a SLOW WALKING RATE along the paper strip from one
end to the other and GENTLY squeeze the bottle as you walk so that blood is
released ONE DROP at a time. Be sure that all the drops land on your paper strip.
•Repeat this procedure using a NORMAL WALKING RATE and a FAST
WALKING RATE.
Walking Direction
Miss the paper? Use a paper
towel to wipe it off the floor!
• When you are done, analyze your results and answer the questions on your
worksheet. Clean up your area and put away your materials before you leave class.
Lab 3 Questions
Use your results to answer these questions.
Draw a sketch of the droplets showing the size, shape, and/or distance between
them at each speed in the chart below.
What did you notice about the shape of the droplets as you increased your walking
speed?
What did you notice about the spines as you increased your walking speed?
What did you notice about the distance between the droplets as you increased your
walking speed?
Which of the three blood droplets shown would have been
created by a wound in the lower part of the leg? Explain.
If you have a blood droplet as shown at left, what does it tell you?
Explain.
If you find a trail of blood with droplets that are round and close together, what
could this mean?
Forensic Science
http://media.popularmechanics.com/images/PMX0706FORENSICSHairSmall.jpg
Presentation developed by T. Trimpe 2006 http://sciencespot.net/
Biology of Hair
Hair is composed of the protein keratin, which is also the primary component of
finger and toe nails.
Hair is produced from a structure called the hair follicle. Humans develop hair follicles
during fetal development, and no new follicles are produced after birth.
Hair color is mostly the result of pigments, which are chemical compounds that reflect
certain wavelengths of visible light.
Hair shape (round or oval) and texture (curly or straight) is influenced heavily by
genes. The physical appearance of hair can be affected by nutritional status and
intentional alteration (heat curling, perms, straightening, etc.).
The body area (head, arm, leg, back, etc.) from which a hair originated can be
determined by the sample’s length, shape, size, color, and other physical
characteristics.
In order to test hair evidence for DNA, the root must be present.
Sources: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair & http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm#Index%20(Hairs)
Hair Structure
Hair is composed of three principal parts:
Cuticle – outer coating composed of overlapping scales
Cortex – protein-rich structure around
the medulla that contains pigment
Medulla – central core
(may be absent)
The structure of hair has been compared to that of a pencil with the
medulla being the lead, the cortex being the wood and the cuticle
being the paint on the outside.
http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
Hair Structure
Cuticle
The cuticle varies in:
• Its scales,
How many there are per centimeter,
How much they overlap,
Their overall shape, and
How much they protrude from the surface
• Its thickness, and
• Whether or not it contains pigment.
Characteristics of the cuticle may be important in distinguishing
between hairs of different species but are often not useful in
distinguishing between different people.
Info: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
Image: http://www.hairdressersus.com/micro/Image5b.jpg
Hair Structure
Cortex
The cortex varies in:
• Thickness
• Texture
• Color
• Distribution of the cortex is perhaps the most important component
in determining from which individual a human hair may have come.
• Microscopic examination can also reveal the condition and shape of
the root and tip.
Info: http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
Image: http://www.extrapersonality.com/hair.html
Hair Structure
Medulla
The medulla may vary in:
• Thickness
• Continuity - one continuous structure
or broken into pieces
• Opacity - how much light is able to
pass through it
• It may also be absent in some species.
Like the cuticle, the medulla can be important for
distinguishing between hairs of different species, but often
does not lend much important information to the
differentiation between hairs from different people.
http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair
http://www.bfro.net/images/whatis/figures/Fig.%203%20with%20caption.jpg
Fiber Evidence
A fiber is the smallest unit of a textile material that has a length many times
greater than its diameter. A fiber can be spun with other fibers to form a yarn that
can be woven or knitted to form a fabric.
The type and length of fiber used, the type of spinning method, and the type of
fabric construction all affect the transfer of fibers and the significance of fiber
associations. This becomes very important when there is a possibility of fiber
transfer between a suspect and a victim during the commission of a crime.
Matching unique fibers on the clothing of a victim to fibers on a suspect’s clothing
can be very helpful to an investigation, whereas the matching of common fibers
such as white cotton or blue denim fibers would be less helpful.
The discovery of cross transfers and multiple fiber transfers between the suspect's
clothing and the victim's clothing dramatically increases the likelihood that these
two individuals had physical contact.
http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm#Fiber%20Evidence
Natural Fibers
Many different natural fibers that come from plants and animals are used in the
production of fabric.
Cotton fibers are the plant fibers most commonly used
in textile materials
The animal fiber most frequently used in the
production of textile materials is wool, and the most
common wool fibers originate from sheep.
http://www.fireflydiapers.com/articles/diaperarticle_naturalfibersabsorb.htm
Synthetic Fibers
More than half of all fibers used in the production of textile
materials are synthetic or man-made.
Nylon, rayon, and polyester are all examples of synthetic
fibers.
Cross-section of a
man-made fiber
Fibers under a microscope
Images: http://www.trashforteaching.org/phpstore/product_images/YarnWS.JPG
http://www.fbi.gov/hq/lab/fsc/backissu/july2000/deedric3.htm#Fiber%20Evidence
http://www.jivepuppi.com/images/fiber_evidence.jpg
It’s time to examine
some hairs and fibers!
http://micro.magnet.fsu.edu/primer/techniques/polarized/gallery/images/humansmall.jpg
Hair & Fiber Identification Lab
Directions:
Your team will need to use a microscope
to document all the hairs and fibers in
your set.
Write the name of the hair or fiber on the
line and then draw what you see under
medium or high power. Be sure to
indicate the power of magnification!
Add a description that highlights the
unique characteristics of each hair and
fiber sample.
Pay attention to details to help you
identify samples during the Hair & Fiber
Challenge activity.
Can you identify the animal hairs shown?
Think About It …
(1)In which samples are we viewing the cuticle? How do they compare?
(2) In which samples are we viewing the medulla? How do they compare?
(3) What characteristics can be used to identify hair samples?
Can you identify the types of fibers shown?
Think About It …
(1)Which samples are natural fibers?
(2) Which samples are synthetic fibers?
(3) What characteristics can be used to identify fiber samples?
Answer
Keys
http://micro.magnet.fsu.edu/primer/techniques/polarized/gallery/images/humansmall.jpg
Types of Animal Hairs - Key
A
Cat
B
Horse
C
Pig
D
Human
G
E
Deer
F
Dog
Rabbit
H
Rat
I
Human
Types of Fibers - Key
Acrylic Yarn
Cotton Yarn
Nylon Rope
Polyester Yarn
Rayon Rope
Wool Yarn