Forensic Science and Criminalistics

1
Introduction

• Forensic Science and Criminalistics

2
Scientific Method

• Empirical Evidence
• Knowledge gained from direct observation
• Analysis
• Studying an unknown item to determine its
  characteristics
• Comparison
• Determining how the characteristics compare with
  the properties of known items.
• Evaluation
• Assessing similarities and differences for
  identification purposes

3

• Forensic
• Characteristic of, or suitable for, a court of
  law.
• Forensic Science
• The application of science to the law.
• Fields of specialization
• Toxicology, psychology, anthropology, chemistry,
  odontology, serology, fingerprints, firearms,
  impressions and tool marks, trace analysis,
  questioned documents.

4
Individualization

• No two things in nature are exactly the same.
• Examples snowflakes, fingerprints, gun barrels,
  lip impressions, shoeprints, pieces of broken
  glass.
• Class Characteristics
• Evidence can be associated only with a group and
  never with a single source
• Individual Characteristics
• Evidence can be associated with a common source
  with a high degree of probability

5
The Modern Crime Laboratory

• Physical Science Unit
• Chemistry, physics, and geology are used in the
  comparison of crime scene evidence (drugs, glass,
  paint, explosives, soil)
• Biology Unit
• DNA profiling, comparison of hairs and fibers,
  comparison of wood and plants.

6

• Firearms Unit
• Examination of firearms, discharged bullets,
  cartridge cases, shotgun shells, and ammunition
  of all types. Also includes examination of
  firearm residues and tool marks.
• Document Examination Unit
• Analysis of paper, ink, typewriters, handwriting,
  depressions, erasures, and burned or charred
  documents.

7

• Photography Unit
• Examine and Record photographic evidence,
  including digital imaging, infrared, ultraviolet,
  and X-ray photography.
• Toxicology Unit
• Examination of body fluids and organs for the
  presence of drugs and poisons.
• Latent Fingerprint Unit
• Processing and examination of evidence for latent
  fingerprints.

8

• Voiceprint Analysis Unit
• Use of the sound spectrograph to tie a voice
  (from a telephoned threat or tape-recorded
  message) to a particular suspect. The instrument
  transforms a voice into a visual graphic display
  called a voiceprint.
• Evidence Collection Unit
• Specially trained personnel go to the crime scene
  to collect and preserve physical evidence for
  later processing at the crime laboratory.