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Forensics by dandanhuanghuang


Methods of Identification
Why is forensics important?
What is Forensic Science?

     Forensic science is the application of
      scientific techniques to investigate a
     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
     What kind of questions can Forensic
      Science help us Answer? (Student
           Forensic Scientists
   Forensic scientists will help to collect
    scientific evidence at a crime scene.
   They can be specialists in a variety of fields:
                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
   It can often be difficult to determine the remains of
    a dead person, especially if all that remains are
   However without proper identification it can be
    difficult to determine the identity of the living as
   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
          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
                 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:
                         Has limitations if used as the sole means
                          of identification
                         Positive identification by a witness looking
                          at an album of photos is difficult.

Tony Mokbel
Identikit and Composite
            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:
                    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

   The Program will flash a face up for 10 seconds
   You then have to reconstruct that face by selecting
    individual features
Biometric Facial Recognition
                 Specialized computer
                  systems and software
                  can quickly and
                  accurately identity a
                  person from a single
                  stored image in a
                 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 are found
          on the palms of hands
          and soles of feet of all
         They allow us to grip
         Each fingerprint
          consists of ridges and
         These will grow back in
          the exact some pattern
Fingerprinting Cont.
                     Fingerprints are
                      compared in the
                      following manner:
                          The same
                           minutiae are
                          The minutiae
                           flow in the same
                          The minutiae
                           occupy the same
                           relative positions
                           to each other
Activity: Super Prints!
            Make a small bowl from the aluminum
             foil and place into a container
            Place a small cup of hot water in the
            Press you finger onto a microscope
            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
            Once the finger print has formed see if
             you can identify some of the minutiae
             that are present
    Project: Design your own crime
   The major piece of assessment for this unit will be a self designed
   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:
             Finger prints
             DNA tests
             Handwriting analysis
             Video surveillance
   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:
             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:
        Finalization of project work (Single lesson)
        Presentation and assessment of work by peers (Double lesson)
      Additional Resources

 List of forensic terminology:
 http://suicideandmentalhealthassociatio
From the eye to DNA
Iris and Retina Identification
               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:
                   Two scans are taken (one for each
                   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
            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
              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

   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
            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                          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

   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
   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
   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
   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?
             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
             Your job is to work out who is the
              father by comparing the DNA
             Remember bands present in the
              child have to come from either its
              mother or father.
Is it real?
How do you Prove a
Document is real?
       Analysis of Handwriting
   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!

   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
   Your partner will now attempt to copy your
   Pass the piece of paper to a third person and
    see if they can spot which signature is the
Printer Matching
        Print outs from a specific
         computer can be matched
         by how the printer leaves
         marks on the paper as the
         paper passes through the
        This can be seen at low light
         and photographed.
        Additionally the ink from the
         printer can also be matched.
                   Ink Analysis
   Each brand of ink has
    its own “chemical
   Slight variations in the
    chemical make-up of
    different brands of ink
    cause it to leave a
    different pattern when
   Slight variations in the
    chemical make-up of
    different brands of ink
    cause it to leave a
    different pattern when
          Activity: Ink Analysis

   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
   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
   Problems associated with the method used in class:
       Destructive test (can‟t do it if evidence must be
       Difficult to differentiate between inks with a very similar
        signature with the naked eye.
       “Crude” method of identification.
   Other non-destructive methods of forensic ink
       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
       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:
               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
Collecting Evidence
         What is evidence?

 Wherever you go and whatever you do
  you leave behind proof that you were
 In a criminal investigation this is called
 Evidence can come in various forms.
Can you think of
different types of
evidence you might
find at a crime scene?
Types of evidence
            Evidence could be:
                Eyewitness – they
                 can give written or
                 verbal accounts.
                Physical evidence:
                     Fingerprints
                     Shoe prints
                     Hair or fibers
                     Blood
                     Digital evidence
            Collecting Fingerprints

   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

   Fingerprints can be picked up on
    porous surfaces such as:
        Stone
        Raw   or unpolished wood
   Technique involves using high powered
    „Poly lights‟ that cause fingerprints to
     Collecting Body Products and

   Whether a fibre is synthetic or derived from an
    organism it can be examined under a comparison
   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
   Most crimes are committed using a
    variety of tools such as:
               and Knives
        Pistols
        Crow Bars and Wire cutters
        Screw Drivers and Hammers

   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

   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
       Impressions can be left
        behind from our feet, shoes
        or even the tyres of our cars.
       How might tracks be left
       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
       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
       While it is drying collect other tyre
       Now swap your images with
        another group. Can you match the
        impressions to particular tyres?
What are some
factors you have to
consider when
Biological and Technological Evidence
Collecting biological Evidence

   Biological evidence can include the
            Seeds
            Blood
            DNA from bodily secretions
            Microscopic pollen

              Can you think of any other forms of
              biological evidence?
Other Biological evidence
             Water organisms
                    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
                    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
            Insects
                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
            The forensic – Time of Death
             worksheet will be began in
            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

   Electronic evidence can consist of:
            Photographs
            Video footage
            Computer and internet records
            Phone Records

              Can you think of any other forms of
              electronic evidence?
Video Imaging
        CCTV (Closed circuit
         television) are routinely
         used in criminal
         investigations to:
               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!
          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
Data Recovery
      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
      Investigators can use special
       data recovery programs to
       restore data from a computer
    Activity: Image Enhancement

   We will take a number of photos in class of:
               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
Who, what and why?
Who saw it?
         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:
                       License plate details
                       Identifying details about an
                       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
            Activity: Habits

   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
            Modus operandi
   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.
What are some
other types of
MO’s you can
think of?
Who might they be?
         Criminal profilers can use the
          information gained from a crime
          scene and the MO to establish a
          psychological profile of an
         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?

   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
     Blood stains fade with time – therefore
      can indicate the time a crime occurred
What information
could wounds on a
body indicate to
Wounds on the body
         Wounds on the body can
             Whether a blunt or sharp
              object was used on the
             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
What do gunshot injuries tell is?

                  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?

   Three factors to consider in a car crash:
           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
Activity: Piecing it together!

Crime scene thinking and investigation
Crime Scene Thinking
       Ongoing Assessment

                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?
 Ongoing Assessment
          As the clock struck five, ninety-
           year 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
              Is there a reason why
               Mirabel interrupted her
               phone call and went to the
              Did Mirabel rush to the
              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
              Do you think she committed
Crime Scene Investigation
“When you have eliminated the impossible, whatever
  remains, however improbable, must be the truth”

                                  - Sherlock Holmes
   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?
  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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