Comprehensive Study Notes on Forensic Science and Police Science (CSS455)

DEFINITION AND SCOPE OF SCIENCE

  • Conceptual Overview of Science

    • Science is a system of thought and a process of thinking dedicated to acquiring new knowledge and understanding the natural world.
    • It lacks a singular definition but is characterized by four dimensions:
      1. A Body of Knowledge: Differs from other knowledge in content and form; deals with material reality and expresses knowledge in quantifiable terms, concepts, laws, and theories.
      2. A Method of Inquiry: Empirical science uses observation, experimentation, and hypothesis testing. Formal science utilizes concepts, rules, and quantitative theories in a deductive form.
      3. An Instrument of Transformation: The practical application is technology, enabling humanity to explain, predict, and change the world.
      4. An Institution: Involves millions of experts working in laboratories, research centers, and educational institutions worldwide.

  • The Scope and Branches of Science

    • Formal Sciences: Include Mathematics (GeometryGeometry, AlgebraAlgebra, ArithmeticArithmetic), Logic, Theoretical Physics, and Statistics. These are characterized by deductive logic and adherence to strict rules.
    • Empirical Sciences: Deal with materials drawn from experience and physical phenomena observable via senses or instruments. Includes Physics, Chemistry, Biology, and Medical Science.
    • Natural Sciences: Focus on natural objects.
      • Physical Sciences: Physical and inanimate objects (e.g., Chemistry, Geology).
      • Biological Sciences: Living bodies (e.g., Botany, Zoology).
    • Medical and Pharmaceutical Sciences: Human/animal health and drugs.
    • Social Sciences: Societies and institutions (e.g., Sociology, Economics).

  • The Scientific Method

    • Standard steps for reporting information:
      1. Stating the problem.
      2. Formulating hypothesis.
      3. Designing experiments.
      4. Observation.
      5. Collecting data.
      6. Conclusions.

MEANING AND SCOPE OF FORENSIC SCIENCE

  • Etymology and Definition

    • Derived from the Latin forensis, meaning "before the forum." In Roman times, charges were presented in a public forum, and the winner was the one with the sharpest forensic (legal) skills.
    • Forensic Science: The practical application of numerous sciences to solve legal system-related questions in either civil or criminal actions.

  • History of Forensic Science

    • Ancient World: Lacked standards; relied on forced confessions.
    • China (1248): Sung Ci’s Xi Yuan Ji Lu (Collected Cases of Injustice Rectified) recorded using flies to identify a murder weapon (a sickle).
    • Europe (16th-18th Century): Army surgeons and physicians began studying pathology.
    • 18th Century Cases: In 1784, John Toms was convicted using a matching pistol wad from a newspaper in his pocket.

  • Subdivisions of Forensic Science

    • Forensic Accounting: Study of accounting evidence.
    • Computational (Digital) Forensics: Retrieval and interpretation of digital media.
    • Forensic Odontology: Study of teeth and dentition uniqueness.
    • Forensic Entomology: Study of insects in/on human remains to determine time of death.
    • Criminalistics: Processing evidence (DNADNA, prints, trace evidence) in a crime laboratory.

  • Forensic Profiling and DNA

    • DNA Profiling: Also called genetic fingerprinting. Although 99.9%99.9\% of human DNADNA is identical, variable number tandem repeats (VNTRVNTR) loci allow individualization.
    • First reported by Sir Alec Jeffreys in 1984.

TECHNIQUES OF CRIME SCENE INVESTIGATION (CSI)

  • Primary Function

    • To collect, identify, document, and preserve physical evidence to identify and apprehend perpetrators.
    • Difference from Forensics: CSICSI is on-site (field forensics); standard forensics occurs in controlled lab settings.

  • Initial Response and Prioritization

    • Safety First: Ensure no immediate threat; scan for scents like gasoline or gas.
    • Emergency Care: Provide medical aid while minimizing contamination. If a suspect is transported, an officer should accompany them to document "dying declarations."
    • Secure Boundaries: Establish boundaries beyond the initial scope; use tape, cones, and vehicles. It is easier to reduce a boundary than to expand one.

  • Processing the Scene

    • Contamination Control: Follow established entry/exit routes; dispose of tools/equipment between evidence collections.
    • Documentation: Includes photography, video, sketches, measurement, and notes.
    • Evidence Collection: Concentrate on the most transient evidence first. Maintain a "chain of custody."

FORENSIC PSYCHOLOGY AND PROFILING

  • Definitions and Roles

    • Forensic Psychology: The intersection between psychology and the criminal justice system.
    • Malingering: Assessing if a defendant is intentionally faking mental illness.
    • Competency to Stand Trial: Determining if an accused person can appropriately participate in their defense.

  • Criminal Profiling

    • An educated attempt to provide biographical sketches of behavioral patterns.
    • Offender Types:
      1. Organized: Plans ahead, meticulous, high birth order, socially adept.
      2. Disorganized: Spontaneous, depersonalizes victim, low social maturity, lives near the crime scene.

  • Psychological Autopsies

    • Investigative method used to determine the mode of death in equivocal cases (accident vs. suicide).

FORGERY AND COUNTERFEITING

  • Signature Forgery

    • Traced Forgery: Produced via a light box or glass; often lacks habitual pen pressure and appears "jittery."
    • Prevention: Devise an individual signature with flourishes; never sign blank documents; keep records of canceled checks for comparison.

  • Counterfeit Currencies

    • Currency produced without legal sanction to resemble genuine legal tender.
    • Detection Methods:
      • Feel of Paper: Genuine notes are crisp; counterfeits often feel floppy.
      • Intaglio Printing: Genuine notes have raised print.
      • Watermark: Visible when held to light; counterfeit versions lack fine detail.
      • Detector Pens: contain an iodine solution that reacts with starch in wood-based paper (fake) to create a black stain; genuine fiber-based paper does not react.

BALLISTICS AND PROJECTILES

  • Ballistics Defined

    • The science of mechanics dealing with the flight, behavior, and effects of projectiles (bullets, rockets).
    • Internal Ballistics: Events inside the weapon (e.g., firing pin marks).
    • External Ballistics: The flight of the bullet between muzzle and target.
    • Terminal Ballistics: The effect of the projectile on the target.

  • Projectiles

    • Spin-Stabilized: Rotated via rifling in the barrel (approx. 250250 revolutions/sec).
    • Fin-Stabilized: Stabilized by aerodynamic fins; often launched from smooth-bore guns.
    • Sabot: A lightweight carrier used to position a sub-caliber projectile in a gun tube to transmit energy.

LANDMINES

  • Nature of Landmines
    • Victim-triggered explosive devices. Anti-personnel mines are designed to maim rather than kill to drain enemy resources (requiring healthy soldiers to carry the injured).
    • Impact: Devastating to children; leaves agricultural land unusable; causes environmental poisoning through chemicals like Trinitrotoluene (TNTTNT).

FIRE INVESTIGATION

  • The Triangle of Combustion

    • Three elements required for fire: 1. Fuel, 2. Oxygen, 3. Heat.

  • Extinguishing Methods

    • Starvation: Removing the fuel source.
    • Smothering: Limiting the oxygen supply (e.g., via CO2CO_{2} or foam).
    • Cooling: Lowering the temperature below the ignition point (e.g., via water).