forensic

Intro to Forensic Science and Criminalistics

Chapter 1: Overview of Forensic Science

• Forensic: Relating to the law.

• Forensic Science: Scientific methods applied in legal contexts (both civil and criminal cases).

Major Areas of Contribution in Forensic Science

1. Corpus Delicti:
      - Definition: A Latin term meaning "body of the crime"; essential facts indicating that a crime has occurred.
      - Examples:
        - Determination of blood alcohol concentration in DUI cases.
        - Identification of controlled substances in drug possession cases.

2. Evaluation of Statements:
      - Scientific examination analyzes physical evidence objectively, which can validate or contradict statements made by witnesses, victims, or suspects.

3. Identification of Substances:
      - Scientific analysis identifies materials involved in crimes.
      - Examples:
        - Illegal drugs in possession cases.
        - Ignitable liquids in arson cases.
        - Gunshot residues on suspects.

4. Identification of Individuals:
      - Techniques for identifying individuals through physical evidence:
        - DNA from biological materials.
        - Fingerprint analysis.
        - Dental records from skeletal remains.

5. Providing Investigative Leads:
      - Database searches can yield matches:
        - DNA profiles compared with the CODIS database.
        - Fingerprints compared in the AFIS database.

6. Establishing Linkages or Exclusions:
      - Physical evidence links suspects to victims, crime scenes, or instruments involved, and can also exclude individuals from consideration.

Chapter 2: History of Forensic Science

• Mathieu J. B. Orfila (Father of Forensic Toxicology):
    - Notable for the "Lafarge" arsenic poisoning case.

• Alphonse Bertillon:
    - Developed anthropometric identification system in the 1890s but faced limitations in distinguishing prisoners.

• Edmond Locard:
    - Established an early police crime lab in Lyon, France (1910) and introduced the Locard Exchange Principle.

• Scientific Method:
    - Steps: Observation, Hypothesis Development, Testing, Refinement. This method is crucial in crime scene investigations.

Chapter 3: Forensic Specialties

1. Forensic Pathology:
      - Studies diseases to determine causes and manners of death (medical reasons vs. circumstances).

2. Forensic Entomology:
      - Analyzes insect life associated with corpses to help estimate time of death.

3. Forensic Odontology:
      - Examines dental records for identification; utilizes both premortem and postmortem analyses, including bite mark comparisons.

4. Forensic Anthropology:
      - Analyzes human skeletal remains; determines age, stature, gender, and racial origin, as well as detects trauma, abnormalities, and cause of death.

5. Forensic Toxicology:
      - Examines poisons and drugs to assist in determining cause of death.

6. Forensic Psychiatry/Psychology:
      - Evaluates offenders' mental state and may offer treatment; some focus on criminal profiling.

7. Forensic Engineering:
      - Investigates transportation accidents, material, and structural failures.

8. Forensic Computer Science:
      - Analyzes electronic data to aid in criminal investigations, including retrieving deleted information.

Chapter 4: Criminalistics

• Definition: Involves recognition, identification, individualization, and evaluation of physical evidence through scientific methods.
    - 1. Recognition: Identifying potential evidence is crucial.
    - 2. Classification: Group evidence based on characteristics.
    - 3. Individualization: Distinguishes uniqueness among class members through detailed comparison of characteristics.
    - 4. Reconstruction: Seeks to understand the sequence and nature of evidence; involves using the scientific method for hypothesis testing.

Chapter 5: Physical Evidence

• Definition: Objects that establish a crime's occurrence or link criminals to victims.

• Production:
    1. Changes induced at a scene (adding or altering elements).
    2. Imprints and Indentations: 2D marks vs 3D impressions.
    3. Striations: Marks from motion that aid in event reconstruction.
    4. Damage: Unique patterns from physical harm.
    5. Exchange Principle: Mutual transfer of materials upon contact.
    6. Deposited Evidence: Evidence generated without direct contact.

• Classification of Physical Evidence: Can be for identification, individualization, or reconstruction purposes.

• Utilization: Provides insight into perpetrator methods (modus operandi) through database comparisons (IAFIS, CODIS, NIBIN).

• Linkages and Exclusions: Establish connections or dismiss individuals based on evidence, which can support or contravene statements made.

Chapter 6: Crime Scene Processing and Analysis

1. Types of Scenes: Classified by location (indoor/outdoor), nature of crime, size of scene (primary vs secondary).

2. Initial Actions: The responsibilities of first responders include ensuring safety, providing medical assistance, and securing the scene.

3. Steps in Crime Scene Processing:
      - Survey and Recognition: Observing and identifying evidence without disturbing it.
      - Searching Patterns:
        - Zone/Quadrant, Spiral, Grid, Line/Strip searches.
      - Documentation: 3 main methods:
        - Notes (e.g., time, weather, evidence discovered).
        - Sketches (rough and finished versions).
        - Photography (overall, midrange, and close-ups).
        - Video recording for a comprehensive visual layout.
      - Evidence Collection: Methods such as lifting, swabbing, and cutting are used carefully to avoid contamination or destruction.
      - Packaging: Properly packing evidence based on type to prevent degradation.
      - Numbering and Describing: Each piece marked for chain of custody.
      - Analysis and Reconstruction: Understanding the sequence of events through thorough analysis of evidence collected.

Chapter 7: Reconstruction Patterns

• Definition: Used for reconstructing past events (e.g., blood spatter analysis, glass fractures).

• Blood Spatter Patterns: Based on principles of physics, patterns can reveal the movement and position of victims/suspects.
     - Low, medium, and high velocity classifications based on droplet sizes and forces.
     - Angle of Incidence: Shape changes with impact angle; a right angle yields circular stains.
     - Various blood types can indicate actions leading to evidence (e.g., arterial spurts vs. wipe patterns).
     - Factors affecting spatter pattern interpretation include surface texture, temperature and distances involved, and individual actions at the scene.

• Glass Fracture Patterns: Determining the side struck by projectiles through observing fracture patterns.
     - Radial and Tangential Fracture Lines help in determining sequence of forces.

• Track and Trail Patterns: Show movements at crime scenes.
     - Tire and Skid Mark Patterns: Used to reconstruct vehicle accidents.

• Other Recognizable Patterns: Can include clothing arrangement, gunshot residue, and burn patterns that provide clues about events surrounding a crime.

Chapter 8: Fingerprints

• Nature of Fingerprints: Unique identifiers that remain unchanged throughout life; critical for identification purposes.
     - Classifications: Loops (60-65%), Whorls (30-35%), Arches (5%).
     - Structure consists of friction ridges and corresponding minutiae.

• Development of Fingerprints: Categorized into visible, plastic (3D), and latent (requiring development).

• Fingerprint Comparison Methodology: The ACE-V method for analysis, comparison, and verification.

• Preservation Techniques: Methods to enhance and recover fingerprints include powdering, chemical fuming, and illumination techniques for latent prints.

• Comparison of Body Parts and Biometrics: Includes palm/sole prints, skeletal features, bite marks, and voice patterns.

• Identification of Human Remains: Engagement with direct viewing or dental records; aged, sexed, and racially estimated through skeletal remains with the help of DNA profiling in mass disasters.