UGC-NET Forensic Science Study Materials
Chapter 1: Nature of Crime Scene
1.1 Definition and Scope
Legal Definition: A crime scene is legally defined as any location where a crime has taken place and where physical evidence of the crime remains. Courts and law enforcement define crime scenes as spaces that, if properly processed, can provide evidence to establish a crime, a suspect, or a connection between both.
Scientific Perspective: From a forensic viewpoint, a crime scene is a primary source of physical evidence. Forensic scientists analyze the scene to obtain biological, physical, and trace evidence. The crime scene must be methodically documented to reconstruct the criminal events and contribute to the investigation.
Investigative Importance: The crime scene is the core for reconstructing criminal acts. Evidence found here can verify witness statements, link suspects, and identify the methods used in the crime. Forensic evidence from a crime scene is critical for solving crimes and supporting legal proceedings.
For Daily Updates and Practice sheet
1.2 Scientific Principles
Locard’s Exchange Principle: Formulated by Dr. Edmond Locard, this principle states that whenever two objects come into contact, a transfer of material occurs. The principle underpins all forensic work by implying that every interaction leaves trace evidence that can link people, objects, and places.
Physical Evidence Dynamics:
- Transfer Evidence: Evidence that is exchanged when two objects come into contact. Examples include fingerprints, hair, or fibers.
- Pattern Evidence: Created by physical contact; examples are blood spatter, tire impressions, and tool marks.
- Conditional Evidence: Conditions or settings at the scene (e.g., open doors or lights on) that might suggest an event sequence.
- Transient Evidence: Short-lived evidence like smells, temperatures, or physical impressions that can degrade or change quickly.
1.3 Components of Crime Scene
Physical Boundaries:
- Inner Cordon: The immediate area containing evidence, which is most restricted.
- Outer Cordon: Wider perimeter set for secondary security, helping to control access and prevent contamination.
Environmental Factors: Weather conditions, lighting, and temperature can impact the condition of evidence. For example, rain may wash away bloodstains or degrade DNA, while bright lighting can distort the appearance of scene colors in photographs.
Temporal Aspects:
- Golden Hour: The first hour after a crime is discovered, when evidence is most intact and accessible for collection.
Chapter 2: Types of Crime Scenes
2.1 Based on Location
- Indoor Crime Scenes: Residential settings, commercial establishments.
- Outdoor Crime Scenes: Examples: parks, fields, streets, and open fields.
- Conveyance Crime Scenes: Scenes within vehicles like cars, boats, and airplanes.
2.2 Based on Activity
- Primary Crime Scene: Where the initial criminal act occurred.
- Secondary Crime Scene: Additional location where evidence related to the crime is found.
2.3 Based on Condition
- Protected Scenes: Indoor scenes or those with restricted access.
- Unprotected Scenes: More vulnerable to contamination or environmental factors.
For Daily Updates and Practice sheet
Chapter 3: Crime Scene Preservation
3.1 Initial Response Protocols
- First Responder Duties: Scene assessment, safety evaluation, and medical assistance.
3.2 Scene Security Measures
- Physical Barriers: Use of crime scene tape and barricades to limit access.
- Documentation Systems: All personnel must log in and out to maintain scene integrity.
3.3 Evidence Protection Methods
- Environmental Protection: Weatherproof covers for outdoor evidence.
- Contamination Prevention: PPE (Personal Protective Equipment) for investigators.
Chapter 1: Unnatural Deaths
1.1 Classification of Deaths
- Natural Deaths: Typically from illnesses or age-related factors.
- Unnatural Deaths: Includes homicide, suicide, and accidental deaths.
1.2 Death Investigation Protocols
- Initial Assessment: Observe body position, scene details, and potential evidence.
- Documentation: Photos and sketches create a visual record of the scene.
1.3 Post-Mortem Changes
- Livor Mortis: Blood pooling due to gravity, helps estimate time of death.
- Rigor Mortis: Muscle stiffening, indicates time elapsed.
- Algor Mortis: Body cooling, suggests time since death.
Chapter 2: Criminal Assaults
2.1 Types of Assaults
- Physical Assaults: Injuries from force.
- Armed Assaults: Forensic examination focuses on weapon type.
2.2 Investigation Methods
- Evidence Collection: Recovering weapons, analyzing blood spatter, obtaining DNA samples.
Chapter 3: Sexual Offences
3.1 Classification
- Types of Offenses: Includes rape, sexual assault, and statutory offenses.
- Legal Framework: IPC and POCSO Act.
For Daily Updates and Practice sheet
3.2 Investigation Protocol
- Victim Management: Ensuring privacy and sensitivity.
- Evidence Collection: Biological evidence can link suspects.
Chapter 4: Poisoning
4.1 Classification of Poisons
- Organic Poisons: Natural (e.g., plant-based).
- Inorganic Poisons: Metallic, gases, and synthetic substances.
4.2 Investigation Methods
- Scene Investigation: Recover containers or residue.
- Laboratory Analysis: Screening and confirmatory tests.
Chapter 5: Vehicular Accidents
5.1 Types of Accidents
- Single Vehicle Accidents: Rollover, collisions.
- Multiple Vehicle Accidents: Head-on, rear-end, or chain-reaction crashes.
5.2 Investigation Protocol
- Documentation: Recording measurements and mapping the scene.
- Evidence Collection: Recovery of tire marks, debris, and vehicle damage.
Chapter 1: Documentation Methods
- Photography: Proper lighting and positioning.
- Sketching: Detailed sketches with scaled measurements.
Chapter 2: Evidence Collection
- Methods: Swabbing, lifting, and vacuuming.
- Packaging: Proper sealing, labeling, and storage.
Chapter 3: Chain of Custody
- Documentation: Accurate records for evidence handling.
- Storage Protocols: Following correct procedures for storage.
