FORENSIC-CHEMISTRY-Formal-notes

FORENSIC CHEMISTRY & TOXICOLOGY

Definition of Chemistry

• Science dealing with the composition, structure and properties of substances and transformations.

Forensic Chemistry

• Application of chemical principles in legal problem solutions.

• Involves:

  1. Analysis of materials related to legal proceedings.

  2. Covers broader forensic sciences like Legal Medicine and Ballistics.

Scope of Forensic Chemistry

• Chemical analysis in criminal investigations.

• Legal implications in material quality analysis.

• Addresses various forensic sciences.

Roles of Forensic Chemist

• Identify clandestine laboratories.

• Analyze marked bills in extortion cases.

• Handle physical evidence collection (e.g. paraffin casts).

Stages of Forensic Chemist's Work

1. Collection of Evidence

   • Ensure sample sufficiency and individuality.

   • Proper labeling and scaling of samples.

2. Examination of Samples

3. Communication of Results

4. Testifying in Court

Definition of a Chemist

• Registered professional engaged in chemistry practice.

Definition of a Forensic Chemist

• Chemist specializing in analyzing crime scene evidence.

Types of Physical Evidence Found at Crime Scenes

• DNA: hair, bones, bodily fluids.

• Body Fluids: saliva, blood, semen, urine.

• Impressions: tool marks, fingerprints.

• Weapons: firearms, explosives analysis.

• Questioned Documents: handwriting analysis, counterfeit checks.

• Trace Evidence: fibers, soil.

Six Golden Rules of Forensic Chemistry

• Work slowly and thoroughly.

• Maintain meticulous notes.

• Consult colleagues.

• Encourage creative thinking.

• Avoid overly complex theories.

History of Forensic Chemistry

• Origins: Ancient civilizations like Egyptians and Greeks utilized poisons for executions (e.g. Socrates and hemlock).

• Key Historical Events: 1728-1752: Blaine trials & first poison tests. 1836: Marsh test for arsenic. 1863: Reliable blood identification method.

Notable Figures in Forensic Chemistry

• Edmond Locard: Founded a police laboratory and formulated Locard's exchange principle.

• Matthieu Joseph Bonaventure Orfila: Father of modern forensic toxicology.

• Sir Francis Galton: Studied fingerprints' uniqueness.

Forensic Laboratories in the Philippines

• Established through Royal Decree No 188 during Spanish rule.

Crime Laboratory Functions

• Scientific treatments of evidence in criminal cases.

• Offers various forensic services (e.g. DNA tests, autopsies).

Chain of Custody

• A record keeping process documenting the handling of evidence.

• Essential for maintaining integrity in legal procedures.

Evidence Custodian

• Maintains chain of custody and security of evidence.

Blood Composition and Analysis

• Components: Red and white blood cells, platelets, plasma.

• Serology: Studies blood groups and properties; crucial for investigations.

• Blood Stains:

1. Passive: Gravity-created (drip, pool).

2. Transfer: Contact with blood-stained objects.

3. Projected: Resulting from force (gush, spatter).

Blood Examination Methods

• Tests:

1. Preliminary Tests: Identify possible blood presence.

2. Confirmatory Tests: Accurate blood identification (e.g. Hemoglobin presence).

Collection Methods of Blood Evidence

• Swabbing: Collection via moist swabs.

• Cutting Fabric: Removing stained sections.

• Syringe Transfer: For liquid samples.

• Tape-lifting: For dried blood stains.

• Photography: Documenting evidence accurately.

Other Bodily Fluids

• Possible to determine body fluids' blood groups.

Semen Identification

• Consists of: Seminal fluid and sperm cells.

• Examination involves locating and confirming sperm presence (under UV light).

Hair Identification

• Structure: Root and shaft, distinguished between human and animal hair.

• Hair samples are useful for linking suspects to crimes.

Fiber Identification

• Types: Animal, vegetable, and synthetic fibers.

Identification and Comparison of Paper

• Tests for fiber composition, loading materials, sizing, and determining watermarks.

Gunpowder & Explosives

• Types of Gunpowder: Black powder (carbon, sulfur, nitrate) and smokeless powder.

• Explosives Types: Mechanical, atomic, chemical.

Gunshot Residue Detection

• Assessment of distance from shooting through powder residue patterns.

Distance Determination

• Analyzing powder patterns to infer shoot distances and contact wounds.

Glass Analysis

• Types of fractures: radial and concentric.

Moulage and Casting

• Materials: Plaster of Paris and other modern solutions for impressions.

Fingerprint Development Methods

• Chemical and powdering techniques to reveal latent prints.

Metallurgy in Crime Detection

• Useful for weapon examinations, restoration of serial numbers on firearms.

Soil and Dust Trace Evidence

• Soil's unique properties as evidence.

Toxicology

• Study of poisons, highlighting their actions on the body and identifying antidotes.

Types of Poisons

• Classification includes gaseous poisons, organic, and identifying properties and effects on various body systems.

Treatment of Acute Poisoning

• Methods of gastric evacuation and neutralization of poisons.

Summary of Results

• Collection and analysis of various forensic materials, chemical principles applied to legal investigations, and preserving evidence integrity are crucial in forensic science.