Forensic science pre mid-term topics

Overall Comprehensive Notes on Forensic Science

Overview of Forensic Science

  • Definition: Forensic science is the application of science to criminal and civil laws, particularly those enforced by police agencies within the criminal justice system 1.

  • Historical Figures:

    • Mathieu Orfila: Father of forensic toxicology 2.

    • Alphonse Bertillion: Developed the first scientific system of personal identification in 1879 2.

    • Francis Galton: Conducted the first definitive study of fingerprints 3.

    • Leone Lattes: Developed a procedure for determining blood type from dried bloodstains 3.

    • Calvin Goddard: Used a comparison microscope to determine if a particular gun fired a bullet 4.

    • Edmond Locard: Known for Locard's Exchange Principle, which states that when a criminal comes into contact with an object or person, a cross-transfer of evidence occurs 5.

Scene Investigation

  • Documentation of Evidence: Blood spatter, tire marks, and fingerprints must be documented 6.

  • Collection of Evidence: Collect evidence discarded by the perpetrator, including weapons and fired bullets 7.

  • First Responders: Responsibilities include securing the crime scene, detaining suspects, and calling for additional personnel 8.

Autopsy Procedures

  • Definition: An autopsy is the examination of a body after death to determine the cause and manner of death 9.

  • Evidence Collection: Items collected include the victim's clothing, fingernail scrapings, and hair combings 10.

Physical Evidence

  • Definition: Physical evidence includes any object that can establish whether a crime has occurred or link a crime to its victim or perpetrator 11.

  • Types of Evidence: Common types include blood, documents, drugs, and fingerprints 12.

  • Purpose of Examination: Physical evidence is examined for identification or comparison purposes 13.

Drug Dependence

  • Definition of a Drug: A natural or synthetic substance that produces physiological or psychological effects 14.

  • Types of Dependence:

    • Psychological Dependence: Conditioned use of a drug due to emotional needs 14.

    • Physical Dependence: A physiological need for a drug, characterized by withdrawal symptoms 14.

Narcotics

  • Definition: Narcotic drugs relieve pain by depressing the central nervous system 15.

  • Common Narcotics:

    • Morphine: Extracted from opium, used to synthesize heroin 16.

    • OxyContin: Contains oxycodone, prescribed for chronic pain 17.

Alcohol Toxicology

  • Absorption: Alcohol is absorbed into the bloodstream within minutes, with maximum levels reached before elimination 18.

  • Distribution: Alcohol is uniformly distributed in the body's watery portions, which constitute about two-thirds of body volume 19.

  • Blood Alcohol Level Calculation: The elimination rate of alcohol is approximately 0.015 percent per hour 20.

Key Concepts and Definitions

  • Forensic Toxicology: Detecting and identifying drugs and poisons in body fluids, tissues, and organs 21.

  • Locard's Exchange Principle: When a criminal comes into contact with an object or person, a cross-transfer of evidence occurs 5.

Revision Questions

  • What is the role of a forensic scientist?

  • How does the absorption of alcohol vary by beverage type?

  • What are the responsibilities of first responders at a crime scene?

These notes provide a comprehensive overview of the key points from the course material, integrating definitions, important figures, and procedures relevant to forensic science.

Detailed Summary of Chapter 1

1. Introduction to Forensic Science

  • Forensic science is defined as the application of science to criminal and civil laws, particularly those enforced by police agencies within the criminal justice system. This broad definition encompasses various scientific disciplines used in legal contexts. 1

2. Historical Foundations

  • The origins of forensic science can be traced back to key figures who developed essential principles and techniques for identifying and comparing physical evidence. Notable contributors include:

    • Bertillon: Created the first scientific system of personal identification in 1879.

    • Galton, Lattes, Goddard, Osborn, and Locard: Each played a significant role in advancing forensic methodologies. 22

3. Key Figures in Forensic Science

  • Mathieu Orfila: Recognized as the father of forensic toxicology, he laid the groundwork for understanding the effects of poisons and toxins in a legal context.


Detailed Summary of Forensics Chapter 2: Crime Scenes

1. Arrival at the Crime Scene

  • The first responding police officer has several key responsibilities:

    • Acquire medical assistance for injured victims, ensuring that medical personnel do not disturb evidence by approaching victims indirectly.23

    • Detain potential suspects or witnesses to gather statements from victims, witnesses, and suspects.8

    • Call for additional personnel such as other officers or forensic investigators, depending on the nature of the crime scene.24

2. Surveying the Crime Scene

  • Conduct a walkthrough for an initial survey:

    • Locate and document obvious items of evidence.

    • Observe and record the conditions of the scene, paying special attention to items or conditions that suggest the timing of the incident or do not appear to belong.25

3. Searching the Crime Scene

  • For a factual and unbiased reconstruction of the crime, investigators must:

    • Rely on their training and experience to ensure no pertinent evidence is overlooked.

    • Recognize that physical evidence can range from large objects to microscopic traces.26

4. Documentation

  • A finished-sketch diagram is essential for documenting the crime scene accurately. This includes the layout of the scene and the placement of evidence.27

5. Visual Aid

Detailed Summary of Forensics Chapter 2: Crime Scenes

1. Arrival at the Crime Scene

  • The first responding police officer has several key responsibilities:

    • Acquire medical assistance for injured victims, ensuring that medical personnel do not disturb evidence by approaching victims indirectly.23

    • Detain potential suspects or witnesses to gather statements from victims, witnesses, and suspects.8

    • Call for additional personnel such as other officers or forensic investigators, depending on the nature of the crime scene.24

2. Surveying the Crime Scene

  • Conduct a walkthrough for an initial survey:

    • Locate and document obvious items of evidence.

    • Observe and record the conditions of the scene, paying special attention to items or conditions that suggest the timing of the incident or do not appear to belong.25

3. Searching the Crime Scene

  • For a factual and unbiased reconstruction of the crime, investigators must:

    • Rely on their training and experience to ensure no pertinent evidence is overlooked.

    • Recognize that physical evidence can range from large objects to microscopic traces.26

4. Documentation

  • A finished-sketch diagram is essential for documenting the crime scene accurately. This includes the layout of the scene and the placement of evidence.27

5. Visual Aid

Notes on Forensics Chapter 3: Physical Evidence

Summary / Highlights

  • Physical Evidence: Encompasses all objects that can establish whether a crime has occurred or link a crime to its victim or perpetrator. This is crucial for investigations. 11

Types of Physical Evidence

  1. Biological Evidence:

    • Blood, semen, and saliva

    • Fibers

    • Drugs

    • Explosives

    • Fingerprints

    • Firearms and ammunition

    • Glass 12

  2. Non-Biological Evidence:

    • Powder residues

    • Soil and minerals

    • Tool marks

    • Vehicle lights

    • Wood and other vegetative matter 28

Importance of Physical Evidence

  • The ability to recognize and properly preserve physical evidence is vital. If investigators fail to do so, even the most advanced laboratory techniques cannot rectify the situation. 29

Visual Aid

Key Concepts

  • Linking Evidence: Physical evidence plays a crucial role in linking suspects to crimes.

  • Preservation: Proper techniques must be employed to preserve evidence for laboratory examination.

Notes on Chapter 5: Death Investigation

Summary / Highlights

  • Objective of Autopsy: The primary goal is to determine the cause of death. Common causes include:

    • Blunt force injury

    • Sharp force injury

    • Asphyxia

    • Gunshot wound

    • Substance abuse 31.

Key Concepts

1. Autopsy

  • Definition: An autopsy is the examination of a body after death, also known as a postmortem examination. Its purpose is to determine the cause and confirm the manner of death, often for legal proceedings 9.

2. Manner of Death

  • Definition: Refers to the circumstances leading to death. It is classified into five categories on death certificates:

    1. Homicide

    2. Suicide

    3. Accidental

    4. Natural

    5. Undetermined 30.

3. Scene Investigation

  • A critical phase involves reconstructing events that preceded death. All significant details of the scene must be meticulously recorded to aid in the investigation 32.

Visual Aids

Important Notes

  • Understanding the subtle differences between a coroner and a medical practitioner is crucial, particularly regarding their qualifications and roles in death investigations 9.

Notes on Chapter 12: Drugs

Summary / Highlights

  • Definition of Drugs: A drug is a natural or synthetic substance used to produce physiological or psychological effects in humans or other higher-order animals. 14

  • Dependence:

    • Psychological Dependence: Stems from conditioned use of a drug due to emotional needs.

    • Physical Dependence: A physiological need for a drug that leads to withdrawal sickness when use is abruptly stopped. 14

Types of Drugs

  1. Narcotics:

    • Regular use leads to physical dependence.

    • Commonly sourced from opium extracted from poppies. 36

  2. Hallucinogens:

    • Cause significant changes in thought processes, perceptions, and moods.

    • Marijuana: The most well-known and controversial drug in this category, with long-term health effects still largely unknown. 37

  3. Stimulants:

    • Cocaine: Can be snorted or injected; stimulates the brain's pleasure center.

    • Crack: A form of cocaine mixed with baking soda, often smoked.

    • Amphetamines: Cause an initial rush followed by exhaustion and depression. 3839

  4. Depressants:

    • Include alcohol, barbiturates, and tranquilizers.

    • Alcohol suppresses thought processes and muscle coordination by affecting the brain. 40

Key Concepts

  • Addiction: The desire to avoid withdrawal sickness leads to physical dependence or addiction. 41

  • Common Drugs of Abuse: Marijuana and cocaine are noted for their regular use not leading to physical dependence. 41

Visual Aids