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What exactly is Forensic Science?


INTRODUCTION Chapter 1 What exactly is Forensic Science? Forensic science applies the knowledge and technology of science to define and enforce laws. – PowerPoint PPT presentation

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Title: What exactly is Forensic Science?

  • Chapter 1

What exactly is Forensic Science?
  • Forensic science applies the knowledge and
    technology of science to define and enforce laws.

The History of Forensics
  • Mathieu Orfila (Spain)
  • Father of Forensic Science(1787-1853)
  • Established the science of Forensic Toxicology,
    by studying the effects of toxins on animals
  • Alphonse Bertillon (France) (1853-1914)
  • Developed the science of Anthropometry a way of
    taking extensive body measurements to identify
    people. This technique of personal identification
    was considered extremely accurate for 2 decades
    and was eventually replaced by fingerprinting.

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More important people!
  • Francis Galton (1822-1911)
  • Proved the uniqueness of human fingerprints and
    published a book called Finger Prints. Current
    fingerprinting techniques are based on his
  • Leone Lattes (1887-1954)
  • Devised a technique to determine the blood group
    of a dried bloodstain and applied the technique
    to criminal investigations. (The ABO blood
    groups were discovered by a Dr. Karl Landsteiner
    in 1901)

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And more
  • Calvin Goddard (1891-1955)
  • Used microscopy to determine if a bullet was
    fired from a particular gun, and if that compares
    to the suspects weapon and a crime scene bullet.
    Modern firearms examiners still use his
  • Albert S. Osborne (1858-1946)
  • Published a book Questioned Documents, and was
    responsible for the acceptance of documents as
    scientific evidence by courts. Modern document
    examiners still use his book as primary refernce.

A couple more
  • Walter C. McCrone (1916-2002)
  • Did extensive work with microscopy to examine
    forensic evidence.
  • Hans Gross (1847-1915)
  • The first person to write about marrying all arms
    of science (Botany, antropology, chemistry,
    physics, mineralogy, etc.) into one unified
    investigative science Forensics.

Last but not least
  • Edmond Locard (1877-1966)
  • Established Locards Exchange Principle which
    state that, whenever 2 objects come in contact
    with each other, there will be an exchange of
    materials between the two.
  • Therefore, when a criminal comes in contact with
    an object or a person, a cross-transfer of
    evidence occurs. So you can find something of
    the criminal on the victim and vice versa.

  • In 1932, thanks to J. Edgar Hoover, the director
    of the FBI, launched a national lab that would
    offer forensic services to the entire countrys
    law enforcement agencies.
  • Today, the FBI laboratory is the largest and most
    reputable in the world.

Basic Services of a Full-Service Crime Lab
  • Physical Science Unit
  • Biology Unit
  • Firearms Unit
  • Document Examination
  • Photography Unit

Optional Services of a Full-Service Crime Lab
  • Toxicology Unit
  • Latent Fingerprint Unit
  • Polygraph Unit
  • Voiceprint Analysis Unit
  • Evidence-Collection Unit

Specialized Forensic Services
  • These are provided by specialized individuals,
    and are not usually a part of a full-service
    crime lab.
  • Forensic Pathology
  • Forensic Anthropology
  • Forensic Entomology
  • Forensic Psychiatry
  • Forensic Odontology
  • Forensic Engineering

1.Forensic Pathology
  • Investigates sudden, unnatural, unexplained, or
    violent deaths. Questions a forensic pathologist
    must attempt to answer
  • - Who is the victim?
  • - What injuries are present?
  • - When did the injuries occur?
  • - What caused the injuries?
  • - What was the time of death?
  • http//www.pathguy.com/TimeDead.htm
  • If a cause of death cannot be determined by
    external observation of the body, then an Autopsy
    is required.

Autopsy (means to see for oneself)
  • This a medical dissection of a body to determine
    cause of death. Causes of death can be classified
  • - Suicide
  • - Homicide
  • - Accident
  • - Natural causes
  • - Undetermined

Autopsy contd.
  • The early stages of decomposition after death
  • Rigor mortis the muscles first relax, then
    stiffen. The body becomes rigid. Rigor mortis
    occurs within 24 hours after death and terminates
    within 36 hours.
  • Livor mortis Once the heart stops pumping, the
    blood tends to pool in the parts of the body
    closest to the ground due to gravity. The skin in
    these areas appear purplish. However, skin that
    was restricted by belts, etc. will not appear
    purplish. This can help determine if the body
    was moved after death. Livor mortis begins
    immediately after death and continues for up to
    12 hours.

Rigor Mortis
Livor Mortis
Autopsy contd.
  • Algor mortis this is the conditions where the
    body temperature cools and reaches the ambient or
    room temperature. The location, size of body,
    clothing, weather conditions, etc. all play a
    role in algor mortis.
  • Generally speaking, beginning an hour after
    death, the body loses heat at the rate of 1 or
    1.5 degrees Fahrenheit per hour until body
    reaches ambient temperature.

Pallor Mortis
Pallor mortis (paleness of death) is a postmortem
paleness which happens almost instantaneously (in
the 15120 minutes after the death) because of a
lack of capillary circulation throughout the
body. Paleness develops so rapidly after death
that it has little to no use in determining the
time of death.
Other Autopsy Factors
  • Potassium levels in vitreous humor of eye after
    death, cells of the inner eye release potassium
    into the ocular fluid called vitreous humor.
    Examining these levels help determine time of
  • Amount of food in stomach can help determine
    when last meal was eaten.

How long does food take in the GI tract?
50 of stomach contents emptied 2.5 to 3 hours
Total emptying of the stomach 4 to 5 hours
50 emptying of the small intestine 2.5 to 3 hours
Transit through the colon 30 to 40 hours
2. Forensic Anthropology
  • Deals with identification and examination of
    human skeletal remains. Bones degrade at an
    incredibly slow rate. They can tell
  • - Sex
  • - Age
  • - Race / Origin
  • - Type of injury (cause of death?)
  • Forensic anthropologists are often needed to
    identify victims of a mass disaster such as air
    crashes, 9/11 WTC disaster, bombings, etc.

Ways to tell male pelvis from female
spread of ilium female more flared and
cradle-like with anterior iliac spines farther
apart vs. more straight up-and-down in male
shape of hole in ischium smaller and triangular
in female vs. larger and rounded in male angle
across pubic symphysis pubic arch less than 90
(acute angle) and more sharply angled in male,
greater than 90 (obtuse angle) and more rounded
in female inner diameter and distance between
ischia larger in female--big enough for head of
baby to pass through
  • Sometimes forensic anthropologists have to use
    Facial Reconstruction artists to help identify
    the remains.

3. Forensic Entomology
  • The study of insects and their relationship to a
    criminal investigation. Can help determine time
    of death.
  • After death, specific insects become inhabitants
    of the corpse in a specific sequence. Blowflies
    are usually the first to arrive. Knowing the
    life cycles and studying the maggots can help
    determine time of death. Ambient temperatures
    can play a role in insect life cycles, so it can
    be tricky to rely solely on this method.

A Blowfly and its maggots
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4. Forensic Psychiatry
  • The relationship between human behavior and legal
    proceedings is examined. Forensic psychiatry can
    help determine
  • - If a person is fit to stand trial
  • - Suspects behavioral profile
  • - Behavioral patterns of criminals (Profiling)

Susan Smith
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5. Forensic Odontology
  • Using teeth to identify remains. Tooth enamel is
    the hardest substance in the body and usually the
    last to decompose. So teeth can be used (and old
    dental records such as X-rays and casts) to
    identify a body in an unrecognizable condition.

Dental Impressions and Casts
6. Forensic Engineering
  • This aspect of forensic science includes accident
    reconstruction, causes and origins of fires and

Body Mystery
  • http//americasunknownchild.net/Medical.html
  • www.crimelibrary.com

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