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Forensics
Methods of Identification
Why is forensics important?
What is Forensic Science?
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Forensic science is the application of
scientific techniques to investigate a
crime.
Forensic scientists collect and analyze
evidence from a crime scene.
Police use this evidence to find out what
happened and who was responsible.
The evidence can also be used in the
legal system to convict someone of a
crime.
What kind of questions can Forensic
Science help us Answer? (Student
Brainstorm).
Forensic Scientists
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Forensic scientists will help to collect
scientific evidence at a crime scene.
They can be specialists in a variety of fields:
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Psychology
Dentistry
Anthropology
Medicine
IT
However regular police can also collect
evidence at a crime scene if they have been
specially trained.
Forensic methods of
identification
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It can often be difficult to determine the remains of
a dead person, especially if all that remains are
bones
However without proper identification it can be
difficult to determine the identity of the living as
well.
In the past criminals could just change their name
and move to a new location.
What are some forms of identification we use today?
(Quick Student Discussion)
Today we have various methods for identifying
remains and establishing the identity of perpetrators
The Bertillon system
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In 1870 the Chief of Criminal
identification in Paris, Alpharose
Bertillion designed a method for
an identification system.
His system involved measuring
and recording the dimensions of
bony body parts
This was called anthropometry
The assumption was that no two
peoples measurements were
exactly the same
Disadvantage: This method
eventually was retired in 1905
because a man was wrongly
convicted and sent to jail for a
crime his twin brother committed!
Photographic Identification
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In 1854 photography was invented
In the 1870’s it was generally used
with anthropometry for identification
By the 1900’s it was widely used by
itself as a form of identification
Still widely used on various forms of
identification e.g. Drivers licenses
Disadvantage:
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Tony Mokbel
Has limitations if used as the sole means
of identification
Positive identification by a witness looking
at an album of photos is difficult.
Identikit and Composite
Drawings
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Before photographs drawings of
wanted criminals were commonly used
e.g. Wanted Posters
Another System called Identikit gained
popularity in 1960’s because it uses
pre-drawn facial features that can be
slotted together without the need of
an artist.
More recently computerized methods
can be used to create a drawing of a
suspect in minutes.
Disadvantage:
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It is often difficult for a witness to get
all features correct
Only 2% of composition drawings ever
led to a positive identification
Activity : Identikit Challenge
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The Program will flash a face up for 10 seconds
You then have to reconstruct that face by selecting
individual features
http://asistm.duit.uwa.edu.au/forensics/faces/
Biometric Facial Recognition
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Specialized computer
systems and software
can quickly and
accurately identity a
person from a single
stored image in a
database.
Facial recognition
measures the points
between different facial
features (eg Eyes,
nose, ears and chin)
and compares this to
the files on a database
What are some types
of evidence?
Fingerprints
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Fingerprints are found
on the palms of hands
and soles of feet of all
primates
They allow us to grip
things
Each fingerprint
consists of ridges and
valleys
These will grow back in
the exact some pattern
Fingerprinting Cont.
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Fingerprints are
compared in the
following manner:
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The same
minutiae are
present
The minutiae
flow in the same
direction
The minutiae
occupy the same
relative positions
to each other
Activity: Super Prints!
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Make a small bowl from the aluminum
foil and place into a container
Place a small cup of hot water in the
container
Press you finger onto a microscope
slide
Add 10 to 15 drops of superglue into
the bowl
Place the slide into the container and
seal lid
Focus a light or heat lamp on the
container
Once the finger print has formed see if
you can identify some of the minutiae
that are present
Project: Design your own crime
science
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The major piece of assessment for this unit will be a self designed
crime.
In your self designed crime you must include a number of different
pieces of forensic evidence that will conclusive indicate a specific
suspect. These may be things like:
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We will cover a number of these topics and more over the course of
this subject
At the end of each week you must hand in the work you have done on
the project:
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Finger prints
DNA tests
Handwriting analysis
Video surveillance
In the first week this may be general brainstorming or the formation of a story
narrative for your crime.
I will provide you with feedback on what you have submitted
The final three lessons of this unit will be as follows:
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Finalization of project work (Single lesson)
Presentation and assessment of work by peers (Double lesson)
Additional Resources
List of forensic terminology:
 http://suicideandmentalhealthassociatio
ninternational.org/forensicsgloss2.html
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Forensics
From the eye to DNA
Iris and Retina Identification
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A persons identity can also be
identified using a biometric
device, like a retina scanner.
These scanners will either
examine the iris pattern or the
blood vessels in the eye
These type of scanners are more
accurate because:
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Two scans are taken (one for each
eye)
Cannot be forged with a glass eye
There are 266 identifiable features
in the iris (this makes it far more
accurate than a fingerprint)
Iris does not change over time
Forensic Odontology and
anthropology
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Odontology is the scientific
study of teeth.
Odontology is often used by
forensic scientists to identify
a victim by his or her teeth
Forensic anthropology is
the application of the
science to study the remains
of a human skeleton
Identifying a ‘known’ body
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If there is sufficient evidence
to assume the identity of a
body (e.g. recovered from a
house fire), x-rays of the body
may be performed.
X-rays will show if any
previous bone breaks have
occurred or whether pins for
serious breaks are present.
These are then compared to
hospital records for the
suspected victim
Additionally X-rays of the teeth
are taken to compare to dental
records as well
Identifying an “Unknown” body
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It can sometimes be difficult to identify a corpse, especially if it
is only a skeleton or individual bones.
However a forensic anthropologist can gather information
about the body from careful examination of the bones. For
example:
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Femur (main bone of the leg) can be measured to determine the
height of a person.
Whereas sex and age can be determined from examination of the
pelvis and skull.
Activity: Inferring height form
bone length
Femur
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Humerus
In this activity you will measure various class
members femurs
From this data we can try to infer the height of
people in the class.
We will then check our results for accuracy!
Check handout for more information
DNA Profiling
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DNA or Deoxyribonucleic acid is a very important molecule found in
all living cells.
Its structure carries genetic information or a blueprint for an entire
organism.
We get half of our DNA from both parents and as a consequence
DNA is unique to an individual, except identical twins.
DNA fingerprinting or profiling was first used as technique in 1985
and was initially used to identify genetic diseases. It was used soon
after in forensic science and criminal investigations
DNA – Deoxyribonucleic acid
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The process begins with a
blood or cell sample from which
DNA is extracted.
The DNA is cut into fragments
The fragments are then
separated by size via
electrophoresis on an agarose
gel.
The DNA band pattern can then
be transferred to a nylon
membrane or a photograph can
be taken.
The band pattern formed is
unique to every individual
(except twins)
Activity: Who’s the father?
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On left we can see two examples
of DNA fingerprints one is
simplified and the other complex.
On your handout are somewhat
simplified DNA profiles for a child,
its mother and two possible
fathers.
Your job is to work out who is the
father by comparing the DNA
bands!
Remember bands present in the
child have to come from either its
mother or father.
Forensics
Is it real?
How do you Prove a
Document is real?
Analysis of Handwriting
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When we analysis handwriting we are trying
to prove the identity of the writer.
This could be from a Ransom note or simply
a signature on a check.
Activity: Handwritten forgery!
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On a piece of paper sign your name twice.
Circle one of the signatures (this will be the
reference sample)
Now swap the piece of paper and pen with a
partner
Your partner will now attempt to copy your
signature
Pass the piece of paper to a third person and
see if they can spot which signature is the
forgery!
Printer Matching
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Print outs from a specific
computer can be matched
by how the printer leaves
marks on the paper as the
paper passes through the
printer
This can be seen at low light
and photographed.
Additionally the ink from the
printer can also be matched.
Ink Analysis
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Each brand of ink has
its own “chemical
signature”.
Slight variations in the
chemical make-up of
different brands of ink
cause it to leave a
different pattern when
dissolved
Slight variations in the
chemical make-up of
different brands of ink
cause it to leave a
different pattern when
dissolved
Activity: Ink Analysis
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Draw a single dot or a line on a strip of chromatography paper.
Approximately 4 cm from the bottom of the paper.
Fill a small beaker with ethanol so the liquid is only 1 to 2 cm
high.
Place your strip of paper into the beaker so that only 1 to 2 cm
is submerged and that your dot or line is only a few cm away
from the ethanol.
Ink Analysis
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Problems associated with the method used in class:
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Other non-destructive methods of forensic ink
analysis:
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Destructive test (can’t do it if evidence must be
preserved)
Difficult to differentiate between inks with a very similar
signature with the naked eye.
“Crude” method of identification.
Infrared luminescence/reflectance (where infrared is
used to identify chemical signatures.
Capillary electrophoresis (where a tiny amount
(nanoliters) of the ink is injected into a silica capillary filled
with a buffer solution, then an electrical current is passed
through it.
Databases for these two methods are currently being
compiled.
Forgery
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Many criminals attempt to
forge many types of
currency or other documents
Therefore the government
and banks have developed
technologies to make it
more difficult to make
successful forgeries.
Upon closer examination of
forged bills some common
mistakes are:
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Identical serial numbers
Poor printing paper
Differences in printer inks
Lack of UV markers
How could we
make documents
harder to Forge?
Anti-Forgery technologies
Forensics:
Collecting Evidence
What is evidence?
Wherever you go and whatever you do
you leave behind proof that you were
there.
 In a criminal investigation this is called
evidence.
 Evidence can come in various forms.
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Can you think of
different types of
evidence you might
find at a crime scene?
Types of evidence
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Evidence could be:
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Eyewitness – they
can give written or
verbal accounts.
Physical evidence:
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Fingerprints
Shoe prints
Hair or fibers
Blood
Digital evidence
Collecting Fingerprints
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A common for of evidence is the finger print.
Fingerprints are formed from contact with non-porous surfaces:
 Glass
 Plastic
 Mirrors / Windows
 Steering wheels
Light colored surfaces are ‘dusted’ with a black carbon powder,
while white aluminum powder is used for dark surfaces.
Porous surface fingerprints
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Fingerprints can be picked up on
porous surfaces such as:
 Stone
 Raw
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or unpolished wood
Technique involves using high powered
‘Poly lights’ that cause fingerprints to
fluoresce
Collecting Body Products and
Fibres
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Whether a fibre is synthetic or derived from an
organism it can be examined under a comparison
microscope.
However finding a match from one fibre at a crime
scene and one from a suspect is strong
circumstantial evidence but not conclusive
What are some
other biological
forms of evidence?
Collecting Impressions –Tool
Marks
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Most crimes are committed using a
variety of tools such as:
 Pistols
and Knives
 Crow Bars and Wire cutters
 Screw Drivers and Hammers
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When criminals use these tools to
commit a crime they can leave behind
marks or damage to material or
persons they come into contact with.
Tool Marks
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The marks made are generally lines (called
Striations) are caused because of imperfections on
the surface of the tool.
Tools used on human tissues do not generally leave
marks or striations.
However wounds found on a victim can generally
indicate, the size, shape and length of a weapon.
Track Impressions
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Impressions can be left
behind from our feet, shoes
or even the tyres of our cars.
How might tracks be left
behind?
Despite that shoes and tyres
are mass produced to be
identical there are still slight
Imperfections that can tell
individual tracks apart.
Activity: Tyre Prints
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Paint a small section of each tyre
with black paint
Place paper on the section that has
been painted
Peel the paper off and wait for it to
dry.
While it is drying collect other tyre
samples
Now swap your images with
another group. Can you match the
impressions to particular tyres?
What are some
factors you have to
consider when
collecting
evidence?
Forensics:
Biological and Technological Evidence
Collecting biological Evidence
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Biological evidence can include the
following:
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Seeds
Blood
DNA from bodily secretions
Microscopic pollen
Can you think of any other forms of
biological evidence?
Other Biological evidence
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Water organisms
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In cases of drowning, water
based organisms like
Diatoms. Diatoms are partly
made of a substance called
silica, which can from long
lasting shapes even after
death.
Different bodies of water will
have different colonies and
populations of diatoms and
this can be used to pinpoint
the location of where the
drowning occurred.
Other Biological evidence
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Insects
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Insects can be important in
determining both the location
and the time of death .
Time can be determined
because insects have very
specific life cycles throughout
the year.
Whereas the location will
depend on the are or
ecosystem the insect is
derived from.
Activity: Time of Death
Worksheet
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The forensic – Time of Death
worksheet will be began in
class
It includes information about
life-cycles of various insects
Use this information to
determine the time of death in
different cases
Whatever you don’t complete in
class do as homework!
Collecting electronic evidence
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Electronic evidence can consist of:
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Photographs
Video footage
Computer and internet records
Phone Records
Can you think of any other forms of
electronic evidence?
Video Imaging
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CCTV (Closed circuit
television) are routinely
used in criminal
investigations to:
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Establish the time a crime
was committed
To identify perpetrators
Footage can be paused
and investigators can
use computer software
to enhance images for
crucial details
Mobile Tracking!
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When you mobile phone
is switched on it can be
used to locate you!
Mobiles can be tacked
down to approximately a
100 metre radius
Criminals however might
use this as an alibi or
could plant someone else
phone at the scene of a
crime!
Data Recovery
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Everything you do on your
computer is recorded
When you format or delete
something it still exists on your
hard drive as machine code (1’s
and 0’S)
What you erase is the way the
computer accesses the machine
code
Investigators can use special
data recovery programs to
restore data from a computer
Activity: Image Enhancement
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We will take a number of photos in class of:
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Car number plates
Or students from a distance
Street Signs
These images will be taken at a distance so the object of the
photo is somewhat unclear
We will then use various image programs on a computer to
attempt to enhance the image
Forensics:
Who, what and why?
Who saw it?
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Eyewitness accounts can be
integral part of establishing
how or why a crime occurred
This is especially true if
witnesses are familiar with the
victim or the offender
Sometimes eyewitness account
provide crucial details about a
crime like:
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License plate details
Identifying details about an
offender
Arguments or sounds they
might have heard
Police always try to get
eyewitness accounts as soon as
possible, because as time goes
on the reliability of a witnesses
memory deteriorates.
What they do by habit
A criminal habit is called a modus
operandi or ‘MO’.
 It refers to a preferred method of
committing a crime
 This becomes more apparent over time
as a criminals skills improve
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Activity: Habits
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Write down your daily habits:
Consider in what order you do things from
the moment you get up to when you get
to school
 Do you do similar things every morning?
 Are there things you do only on some
mornings?
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Modus operandi
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Some examples of ‘MO’ are:
Murder: serial murders usually have a
defined technique for committing a murder
and getting rid of the remains
 Time and date: Some criminals may
commit crimes during certain times. Could
indicate whether they are unemployed,
single or work during the day.
 Location of similar offenses: Repeat
criminals often commit crimes in areas
they are familiar with.
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What are some
other types of
MO’s you can
think of?
Who might they be?
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Criminal profilers can use the
information gained from a crime
scene and the MO to establish a
psychological profile of an
offender.
Profilers may also use information
about the location of crimes to
narrow down where a new crime
is likely to occur
However criminal profilers can
sometimes be a hindrance to an
investigation because police can
overlook a suspect because they
do not fit a certain profile
What does a bloody mess tell us?
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In a violent crime such as a murder
there is usually a lot of blood present at
the scene. Blood patterns can :
Indicate a weapons striking movement
 Indicate the movement of a victim and an
offender
 Blood stains fade with time – therefore
can indicate the time a crime occurred
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What information
could wounds on a
body indicate to
us?
Wounds on the body
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Wounds on the body can
indicate:
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Whether a blunt or sharp
object was used on the
victim
Wounds found on the
right side of a victim may
indicate the offender was
left handed.
Pieces of a weapon or
fibres from the offender
may be caught in the
wound.
What do gunshot injuries tell is?
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The height and direction of
bullets can be determined by
drawing a line from the
wound in a victim or from a
bullet lodged in a wall
In an autopsy a entry wound
will be small while a exit
wound will be large.
During an autopsy a bullet
may be recovered which can
later be matched to an
offenders weapon.
Why did a car crash occur?
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Three factors to consider in a car crash:
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The vehicles involved
The environmental conditions
The condition of the drivers
The biggest factor in a crash is usually driver error
Skids marks on the road can indicate how a crash
occurred and the speed that vehicles were traveling
at.
Activity: Piecing it together!
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http://www.discoverychannel.co.uk/crime/csi/
Forensics:
Crime scene thinking and investigation
Crime Scene Thinking
Ongoing Assessment
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Amy La Tour’s body was
found in her bedroom last
night, as shown, with her
pet canary strangled in its
cage. Henry Willy and Joe
Wonty, her boyfriends;
Louis Spanker, a burglar
known to have been in the
vicinity; and Celeste, her
maid, were questioned by
the police.
Can you solve the case?
Dropout
Ongoing Assessment
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As the clock struck five, ninetyyear old Mrs. Mirabel Fallwell
dropped out of the window of
her spacious twelfth-floor
apartment. On the fourth stroke
she struck.
Detective Amos Shrewd
investigated shortly afterwards
and found the room as you see
it. Jerry Jarvis, Mrs. Fallwell’s
nephew and heir, said that the
portrait on the wall of his
beloved aunt was one he
himself had painted. Under
questioning, he claimed that he
had been at the far end of the
apartment at the time of the
tragedy and that he knew
nothing about it until informed
by the police.
Would you charge Jarvis with
homicide and why?
Dropout - Hints
Ongoing Assessment
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Is there a reason why
Mirabel interrupted her
phone call and went to the
window?
Did Mirabel rush to the
window?
Is it likely that she brought a
footstool to the window?
Is it reasonable to suppose
that Mirabel had a dizzy
spell at the window?
Did she try to keep herself
from falling out of the
window?
Do you think she committed
suicide?
Crime Scene Investigation
“When you have eliminated the impossible, whatever
remains, however improbable, must be the truth”
- Sherlock Holmes
Scenario
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Dr. Wilson Sherwood was working late in his
office keen to avoid the two women in his
life; Annette Jennings and Cara Banner. Both
had recently found out that he was dating
them at the same time.
Both were not exactly happy with him.
The following morning (5/8/07) Janice Hurley
– a co worker of Dr. Sherwood – discovered
his body, a suicide note and a bottle of
morphine pills.
Was it suicide or something more?
Evidence
Performance for Understanding
Solving the Mystery
Each group has the same case file
 Within the Group you will discuss and
solve the case
 Each group must present their case to
the class with justifications based on
any evidence they have.
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