Forensic Science

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Forensic Science

• Definition and Background

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What is Forensic Science?

• The application of science to those criminal and
  civil laws that are enforced by police agencies
  in a criminal justice system.
• i.e. any application of science to law
  enforcement
• Includes geology, chemistry, physics, biology,
  etc.

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• Criminalistics any of the services provided by
  a crime lab
• For all intents and purposes, the term is
  interchangeable with forensic science

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Sir Arthur Conan Doyle

• Author of the Sherlock Holmes series (late 1800s
  early 1900s)
• Popularized forensic investigation through his
  novels
• Used up-and-coming detective methods in his
  stories, including fingerprinting, serology,
  firearm identification, and questioned documents

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Major contributors to the field

• Mathieu Orfila (1787-1853) father of toxicology
  the science of dealing with poisons and their
  effects.
• Alphonse Bertillon (1853-1914) developed
  science of anthropometry the taking of a series
  of body measurements for means of personal
  identification (later replaced by more reliable
  fingerprinting)

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• Francis Galton (1822-1911) first thorough study
  of fingerprints and how to classify them offered
  statistical proof of their uniqueness
• Leone Lattes (1887-1954) developed procedure
  for determining the ABO blood type of dried blood
  stains

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• Calvin Goddard (1891-1955) popularized the use
  of comparison microscopes for matching bullets
  with weapons
• Albert S. Osborn (1858-1946) authored
  Questioned Documents, a reference book for
  document examiners

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• Hans Gross (1847-1915) wrote Criminal
  Investigation and Criminology, books detailing
  how the sciences are incorporated into crime
  scene investigation

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• Edmond Locard (1877-1966) created the first
  rudimentary crime lab in Lyons, France.
• Locards Exchange Principle when a criminal
  comes in contact with an object or person, a
  cross-transfer of evidence occurs
• Every criminal can be connected to his/her crime
  scene by something as small as dust particles
  carried to or from the scene

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Locard cont..

• First to request that suspects clothing be
  examined in the lab
• His success led to the establishment of police
  labs in Vienna, Berlin, Sweden, Finland, and
  Holland

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FBI

• Under director J. Edgar Hoover, national lab for
  forensic services established in 1932
• FBI lab is now the worlds largest, with 1
  million examinations each year

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• (1984) Alec Jeffreys developed the first DNA
  profiling test.

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Types of Evidence
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Direct Evidence

• Proves a fact without necessity of an inference
  or presumption
  example testimony by a
  completely credible witness that proves the fact
  stated in the testimony A doctor testifying the
  body dies from asphyxiation

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Circumstantial evidence

• Circumstantial evidence is best explained by
  saying what it is not - it is not direct evidence
  from a witness who saw or heard something.
  Circumstantial evidence is a fact that can be
  used to infer another fact.
• Ex A man is accused of embezzling money from his
  company, In the same month he has purchased a few
  big ticket items.

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Testimonial Evidence

• Evidence given by the lay or expert witness
• Principle test for this type of evidence is the
  credibility of the witness

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Physical Evidence

• Physical objects linked to the crime
• Fingerprints, weapons, DNA, clothing, body,
  letter/notes, casings/bullets, hair, skin etc